Weak measurements have been predicted to dramatically alter universal properties of quantum critical wave functions, though experimental validation remains an open problem. Here we devise a practical scheme for realizing measurement-altered criticality in a chain of Rydberg atoms tuned to Ising and tricritical Ising phase transitions. In particular, we show that projectively measuring a periodic subset of atoms alters quantum critical correlations in distinct ways that one can control via the choice of measured sites and the measurement outcomes. While our protocol relies on postselection, the measurement outcomes yielding the most dramatic consequences occur with surprisingly large probabilities: \ud835\udc42\u2061(10%) with chains featuring \ud835\udc42\u2061(100) sites. Characterizing the proposed postmeasurement states requires only an adjustment in the post-process averaging of outcomes used to characterize unmeasured critical states, resulting in minimal additional experimental overhead for demonstrating measurement-altered criticality.
", "doi": "10.1103/dzff-3lxm", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2026-09-09", "series_number": "11", "volume": "137", "issue": "11", "pages": "110403" }, { "id": "authors:3zkgt-yc203", "collection": "authors", "collection_id": "3zkgt-yc203", "cite_using_url": "https://authors.library.caltech.edu/records/3zkgt-yc203", "type": "article", "title": "Observation of conformal field theory spectra in a quantum simulator", "author": [ { "family_name": "Sun", "given_name": "Xiangkai", "orcid": "0009-0006-2582-1018", "clpid": "Sun-Xiangkai" }, { "family_name": "Le", "given_name": "Yuan", "orcid": "0000-0002-0261-5135", "clpid": "Le-Yuan" }, { "family_name": "Naus", "given_name": "Stephen", "clpid": "Naus-Stephen" }, { "family_name": "Tsai", "given_name": "Richard Bing-Shiun", "orcid": "0000-0002-8675-8677", "clpid": "Tsai-Richard-Bing-Shiun" }, { "family_name": "Picard", "given_name": "Lewis R. B.", "clpid": "Picard-Lewis-R-B" }, { "family_name": "Murciano", "given_name": "Sara" }, { "family_name": "Knap", "given_name": "Michael", "orcid": "0000-0002-7093-9502" }, { "family_name": "Alicea", "given_name": "Jason", "orcid": "0000-0001-9979-3423", "clpid": "Alicea-J" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Conformal field theories (CFTs) feature prominently in high-energy physics, statistical mechanics and condensed matter. For example, CFTs govern emergent universal properties of systems tuned to quantum phase transitions, including their entanglement, correlations and low-energy excitation spectra. Much of the rich structure predicted by CFTs nevertheless remains unobserved in experiment. Here we directly observe the energy excitation spectra of emergent CFTs at quantum phase transitions—recovering universal energy ratios characteristic of the underlying field theories. Specifically, we develop and implement a modulation technique to resolve the finite-size spectra of a Rydberg chain, variably tuned to quantum phase transitions described by either Ising or tricritical Ising CFTs. We also use local control to distinguish parities of excitations under reflection and, in the tricritical Ising chain, to induce transitions between distinct CFT spectra associated with changing boundary conditions. By using a variant of the modulation technique, we furthermore study the dynamical structure factor of the critical system, which is closely related to the correlation of an underlying Ising conformal field. Our work not only probes the emergence of CFT features in a quantum simulator but also provides a technique for diagnosing a priori unknown universality classes in future experiments.
", "doi": "10.1038/s41586-026-10904-x", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2026-09-03", "volume": "657", "pages": "98-106" }, { "id": "authors:7dvfe-39d47", "collection": "authors", "collection_id": "7dvfe-39d47", "cite_using_url": "https://authors.library.caltech.edu/records/7dvfe-39d47", "type": "article", "title": "Extending the dynamic range in quantum frequency estimation with sequential weak measurements", "author": [ { "family_name": "Direkci", "given_name": "Su", "orcid": "0009-0002-3867-4337", "clpid": "Direkci-Su" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Gefen", "given_name": "Tuvia", "orcid": "0000-0002-3235-4917" } ], "abstract": "Quantum metrology explores optimal quantum protocols for parameter estimation. In the context of optical atomic clocks, conventional protocols focus on optimal input states and measurements to achieve enhanced sensitivities. However, such protocols are typically limited by phase slip errors inflicted due to the decoherence of the local oscillator. Here, we study schemes to extend the dynamic range and overcome phase slip noise through weak measurements with ancilla qubits. Using coherent spin states, we find optimal weak measurements protocols: we identify optimal measurement strength for any given interrogation time and number of atoms. Then, we combine weak and projective measurements to construct a protocol that asymptotically saturates the noiseless precision limits and outperforms previously proposed methods for phase slip noise suppression.
", "doi": "10.1103/2hyn-cqlq", "issn": "2643-1564", "publisher": "American Physical Society", "publication": "Physical Review Research", "publication_date": "2026-06-10", "series_number": "2", "volume": "8", "issue": "2", "pages": "L022046" }, { "id": "authors:2f39d-pdw64", "collection": "authors", "collection_id": "2f39d-pdw64", "cite_using_url": "https://authors.library.caltech.edu/records/2f39d-pdw64", "type": "article", "title": "Heisenberg-limited Bayesian phase estimation with low-depth digital quantum circuits", "author": [ { "family_name": "Direkci", "given_name": "Su", "orcid": "0009-0002-3867-4337", "clpid": "Direkci-Su" }, { "family_name": "Finkelstein", "given_name": "Ran", "orcid": "0000-0002-4524-5875", "clpid": "Finkelstein-Ran" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Gefen", "given_name": "Tuvia", "orcid": "0000-0002-3235-4917", "clpid": "Gefen-Tuvia" } ], "abstract": "Optimal phase estimation protocols require complex state preparation and readout schemes, generally unavailable or unscalable in many quantum platforms. We develop a scheme that achieves near-optimal precision up to a constant overhead for Bayesian phase estimation, using simple digital quantum circuits with depths scaling logarithmically with the number of qubits. This is done by approximating the optimal initial states with products of Greenberger-Horne-Zeilinger states for Gaussian prior phase distributions with arbitrary widths. We study various protocols that employ this class of states with different levels of measurement and post-processing complexities, and obtain improvement compared to previously proposed schemes. We then use our scheme to address phase slip errors and laser noise, which impose a major limitation in Bayesian phase estimation and atomic clocks. Based on our scheme, we develop an efficient protocol to suppress this noise that outperforms existing methods.
\nOptical tweezer arrays have transformed atomic and molecular physics, now forming the backbone for a range of leading experiments in quantum computing, simulation and metrology. Typical experiments trap tens to hundreds of atomic qubits and, recently, systems with around 1,000 atoms were realized without defining qubits or demonstrating coherent control. However, scaling to thousands of atomic qubits with long coherence times and low-loss and high-fidelity imaging is an outstanding challenge and critical for progress in quantum science, particularly towards quantum error correction (QEC). Here we experimentally realize an array of optical tweezers trapping more than 6,100 neutral atoms in around 12,000 sites, simultaneously surpassing state-of-the-art performance for several metrics that underpin the success of the platform. Specifically, while scaling to such a large number of atoms, we demonstrate a coherence time of 12.6(1) s, a record for hyperfine qubits in an optical tweezer array. We show room-temperature trapping lifetimes of about 23 min, enabling record-high imaging survival of 99.98952(1)% with an imaging fidelity of more than 99.99%. We present a plan for zone-based quantum computing and demonstrate necessary coherence-preserving qubit transport and pick-up/drop-off operations on large spatial scales, characterized through interleaved randomized benchmarking. Our results, along with recent developments, indicate that universal quantum computing and QEC with thousands to tens of thousands of physical qubits could be a near-term prospect.
", "doi": "10.1038/s41586-025-09641-4", "pmcid": "PMC12589140", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2025-11-06", "series_number": "8088", "volume": "647", "issue": "8088", "pages": "60-67" }, { "id": "authors:nbg5p-fj133", "collection": "authors", "collection_id": "nbg5p-fj133", "cite_using_url": "https://authors.library.caltech.edu/records/nbg5p-fj133", "type": "article", "title": "Experimental Signatures of Hilbert-Space Ergodicity: Universal Bitstring Distributions and Applications in Noise Learning", "author": [ { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Mark", "given_name": "Daniel K.", "orcid": "0000-0002-5017-5218" }, { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751" }, { "family_name": "Finkelstein", "given_name": "Ran", "orcid": "0000-0002-4524-5875", "clpid": "Finkelstein-Ran" }, { "family_name": "Scholl", "given_name": "Pascal", "orcid": "0000-0002-5675-4237", "clpid": "Scholl-Pascal" }, { "family_name": "Choi", "given_name": "Soonwon", "orcid": "0000-0002-1247-062X" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Systems reaching thermal equilibrium are ubiquitous. For classical systems, this phenomenon is typically understood statistically through ergodicity in phase space, but translating this to quantum systems is a long-standing problem of interest. Recently, a strong notion of quantum ergodicity has been proposed, namely, that isolated, global quantum states uniformly explore their available state space, dubbed . Here, we observe signatures of this process with an experimental Rydberg quantum simulator and various numerical models, before generalizing to the case of a local quantum system interacting with its environment. For a closed system, where the environment is a complementary subsystem, we predict and observe a smooth quantum-to-classical transition in that observables progress from large, quantum fluctuations to small, Gaussian fluctuations as the bath size grows. This transition exhibits universal properties on a quantitative level among a wide range of systems, including those at finite temperature, those with itinerant particles, and random circuits. For an open system, where the environment is uncontrolled, we predict the statistics of observables under largely arbitrary noise channels including those with correlated errors, allowing us to discriminate between candidate error models both for continuous Hamiltonian time evolution and for digital random circuits. This allows for computationally efficient experimental noise learning and, more broadly, is a new avenue for quantitatively classifying the behavior of noisy quantum systems. Ultimately, our results clarify the role of ergodicity in quantum dynamics, with fundamental and practical consequences.
", "doi": "10.1103/h6xy-zpx4", "issn": "2160-3308", "publisher": "American Physical Society", "publication": "Physical Review X", "publication_date": "2025-07-01", "series_number": "3", "volume": "15", "issue": "3", "pages": "031001" }, { "id": "authors:mb652-0vr66", "collection": "authors", "collection_id": "mb652-0vr66", "cite_using_url": "https://authors.library.caltech.edu/records/mb652-0vr66", "type": "article", "title": "Erasure cooling, control, and hyperentanglement of motion in optical tweezers", "author": [ { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Scholl", "given_name": "Pascal", "orcid": "0000-0002-5675-4237", "clpid": "Scholl-Pascal" }, { "family_name": "Finkelstein", "given_name": "Ran", "orcid": "0000-0002-4524-5875", "clpid": "Finkelstein-Ran" }, { "family_name": "Tsai", "given_name": "Richard Bing-Shiun", "orcid": "0000-0002-8675-8677", "clpid": "Tsai-Richard-Bing-Shiun" }, { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751", "clpid": "Choi-Joonhee" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Coherently controlling the motion of single atoms in optical tweezers would enable new applications in quantum information science. To demonstrate this, we first prepared atoms in their motional ground state using a species-agnostic cooling mechanism that converts motional excitations into erasures, errors with a known location. This cooling mechanism fundamentally outperforms idealized traditional sideband cooling, which we experimentally demonstrated. By coherently manipulating the resultant pure motional state, we performed mid-circuit readout and mid-circuit erasure detection through local shelving into motional superposition states. We lastly entangled the motion of two atoms in separate tweezers and generated hyperentanglement by preparing a simultaneous Bell state of motional and optical qubits, unlocking a large class of quantum operations with neutral atoms.
", "doi": "10.1126/science.adn2618", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2025-05-22", "series_number": "6749", "volume": "388", "issue": "6749", "pages": "845-849" }, { "id": "authors:1m2cv-3ke60", "collection": "authors", "collection_id": "1m2cv-3ke60", "cite_using_url": "https://authors.library.caltech.edu/records/1m2cv-3ke60", "type": "article", "title": "Optimal Conversion from Classical to Quantum Randomness via Quantum Chaos", "author": [ { "family_name": "Mok", "given_name": "Wai-Keong", "orcid": "0000-0002-1920-5407", "clpid": "Mok-Wai-Keong" }, { "family_name": "Haug", "given_name": "Tobias", "orcid": "0000-0003-2707-9962" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Preskill", "given_name": "John", "orcid": "0000-0002-2421-4762", "clpid": "Preskill-J" } ], "abstract": "Quantum many-body systems provide a unique platform for exploring the rich interplay between chaos, randomness, and complexity. In a recently proposed paradigm known as deep thermalization, random quantum states of system \ud835\udc34 are generated by performing projective measurements on system \ud835\udc35 following chaotic Hamiltonian evolution acting jointly on \ud835\udc34\u2062\ud835\udc35. In this scheme, the randomness of the projected state ensemble arises from the intrinsic randomness of the outcomes when \ud835\udc35 is measured. Here, we propose a modified scheme in which classical randomness injected during the protocol is converted by quantum chaos into quantum randomness of the resulting state ensemble. We show that for generic chaotic systems this conversion is optimal in that each bit of injected classical entropy generates as much additional quantum randomness as adding an extra qubit to \ud835\udc35. This significantly enhances the randomness of the projected ensemble without imposing additional demands on the quantum hardware. Our scheme can be easily implemented on typical analog quantum simulators, providing a more scalable route for generating quantum randomness valuable for many applications. In particular, we demonstrate that the accuracy of a shadow tomography protocol can be substantially improved.
", "doi": "10.1103/physrevlett.134.180403", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2025-05-06", "series_number": "18", "volume": "134", "issue": "18", "pages": "180403" }, { "id": "authors:43bqy-49v97", "collection": "authors", "collection_id": "43bqy-49v97", "cite_using_url": "https://authors.library.caltech.edu/records/43bqy-49v97", "type": "article", "title": "Benchmarking and Fidelity Response Theory of High-Fidelity Rydberg Entangling Gates", "author": [ { "family_name": "Tsai", "given_name": "Richard Bing-Shiun", "orcid": "0000-0002-8675-8677", "clpid": "Tsai-Richard-Bing-Shiun" }, { "family_name": "Sun", "given_name": "Xiangkai", "orcid": "0009-0006-2582-1018", "clpid": "Sun-Xiangkai" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Finkelstein", "given_name": "Ran", "orcid": "0000-0002-4524-5875", "clpid": "Finkelstein-Ran" }, { "family_name": "Endres", "given_name": "Manuel A.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "The fidelity of entangling operations is a key figure of merit in quantum information processing, especially in the context of quantum error correction. High-fidelity entangling gates in neutral atoms have seen remarkable advancement recently. A full understanding of error sources and their respective contributions to gate infidelity will enable the prediction of fundamental limits on quantum gates in neutral atom platforms with realistic experimental constraints. In this work, we implement the time-optimal Rydberg controlled-Z (CZ) gate, design a circuit to benchmark its fidelity, and achieve a fidelity, averaged over symmetric input states, of 0.9971(5), downward corrected for leakage error, which together with our recent work [Nature 634, 321–327 (2024)] forms a new state of the art for neutral atoms. The remaining infidelity is explained by an error model, consistent with our experimental results over a range of gate speeds, with varying contributions from different error sources. Further, we develop a fidelity response theory to efficiently predict infidelity from laser noise with nontrivial power spectral densities and derive scaling laws of infidelity with gate speed. Besides its capability of predicting gate fidelity, we also utilize the fidelity response theory to compare and optimize gate protocols, to learn laser frequency noise, and to study the noise response for quantum simulation tasks. Finally, we predict that a CZ gate fidelity of \u22730.999 is feasible with realistic experimental upgrades.
", "doi": "10.1103/prxquantum.6.010331", "issn": "2691-3399", "publisher": "American Physical Society", "publication": "PRX Quantum", "publication_date": "2025-01/2025-03", "series_number": "1", "volume": "6", "issue": "1", "pages": "010331" }, { "id": "authors:v8ycd-8g456", "collection": "authors", "collection_id": "v8ycd-8g456", "cite_using_url": "https://authors.library.caltech.edu/records/v8ycd-8g456", "type": "article", "title": "Maximum Entropy Principle in Deep Thermalization and in Hilbert-Space Ergodicity", "author": [ { "family_name": "Mark", "given_name": "Daniel K.", "orcid": "0000-0002-5017-5218" }, { "family_name": "Surace", "given_name": "Federica", "orcid": "0000-0002-1545-5230", "clpid": "Surace-Federica" }, { "family_name": "Elben", "given_name": "Andreas", "orcid": "0000-0003-1444-6356", "clpid": "Elben-Andreas" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751" }, { "family_name": "Refael", "given_name": "Gil", "clpid": "Refael-G" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Choi", "given_name": "Soonwon", "orcid": "0000-0002-1247-062X" } ], "abstract": "We report universal statistical properties displayed by ensembles of pure states that naturally emerge in quantum many-body systems. Specifically, two classes of state ensembles are considered: those formed by (i) the temporal trajectory of a quantum state under unitary evolution or (ii) the quantum states of small subsystems obtained by partial, local projective measurements performed on their complements. These cases, respectively, exemplify the phenomena of \"Hilbert-space ergodicity\" and \"deep thermalization.\" In both cases, the resultant ensembles are defined by a simple principle: The distributions of pure states have maximum entropy, subject to constraints such as energy conservation, and effective constraints imposed by thermalization. We present and numerically verify quantifiable signatures of this principle by deriving explicit formulas for all statistical moments of the ensembles, proving the necessary and sufficient conditions for such universality under widely accepted assumptions, and describing their measurable consequences in experiments. We further discuss information-theoretic implications of the universality: Our ensembles have maximal information content while being maximally difficult to interrogate, establishing that generic quantum state ensembles that occur in nature hide (scramble) information as strongly as possible. Our results generalize the notions of Hilbert-space ergodicity to time-independent Hamiltonian dynamics and deep thermalization from infinite to finite effective temperature. Our work presents new perspectives to characterize and understand universal behaviors of quantum dynamics using statistical and information-theoretic tools.
", "doi": "10.1103/physrevx.14.041051", "issn": "2160-3308", "publisher": "American Physical Society", "publication": "Physical Review X", "publication_date": "2024-11-25", "series_number": "4", "volume": "14", "issue": "4", "pages": "041051" }, { "id": "authors:d95hb-1jz08", "collection": "authors", "collection_id": "d95hb-1jz08", "cite_using_url": "https://authors.library.caltech.edu/records/d95hb-1jz08", "type": "article", "title": "Universal quantum operations and ancilla-based read-out for tweezer clocks", "author": [ { "family_name": "Finkelstein", "given_name": "Ran", "orcid": "0000-0002-4524-5875", "clpid": "Finkelstein-Ran" }, { "family_name": "Tsai", "given_name": "Richard Bing-Shiun", "orcid": "0000-0002-8675-8677", "clpid": "Tsai-Richard" }, { "family_name": "Sun", "given_name": "Xiangkai", "orcid": "0009-0006-2582-1018", "clpid": "Sun-Xiangkai" }, { "family_name": "Scholl", "given_name": "Pascal", "orcid": "0000-0002-5675-4237", "clpid": "Scholl-Pascal" }, { "family_name": "Direkci", "given_name": "Su", "orcid": "0009-0002-3867-4337", "clpid": "Direkci-Su" }, { "family_name": "Gefen", "given_name": "Tuvia", "orcid": "0000-0002-3235-4917", "clpid": "Gefen-Tuvia" }, { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751", "clpid": "Choi-Joonhee" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Enhancing the precision of measurements by harnessing entanglement is a long-sought goal in quantum metrology. Yet attaining the best sensitivity allowed by quantum theory in the presence of noise is an outstanding challenge, requiring optimal probe-state generation and read-out strategies. Neutral-atom optical clocks, which are the leading systems for measuring time, have shown recent progress in terms of entanglement generation but at present lack the control capabilities for realizing such schemes. Here we show universal quantum operations and ancilla-based read-out for ultranarrow optical transitions of neutral atoms. Our demonstration in a tweezer clock platform enables a circuit-based approach to quantum metrology with neutral-atom optical clocks. To this end, we demonstrate two-qubit entangling gates with 99.62(3)% fidelity—averaged over symmetric input states—through Rydberg interactions and dynamical connectivity for optical clock qubits, which we combine with local addressing16 to implement universally programmable quantum circuits. Using this approach, we generate a near-optimal entangled probe state, a cascade of Greenberger–Horne–Zeilinger states of different sizes, and perform a dual-quadrature Greenberger–Horne–Zeilinger read-out. We also show repeated fast phase detection with non-destructive conditional reset of clock qubits and minimal dead time between repetitions by implementing ancilla-based quantum logic spectroscopy for neutral atoms. Finally, we extend this to multi-qubit parity checks and measurement-based, heralded, Bell-state preparation. Our work lays the foundation for hybrid processor–clock devices with neutral atoms and more generally points to a future of practical applications for quantum processors linked with quantum sensors.
", "doi": "10.1038/s41586-024-08005-8", "pmcid": "PMC11464380", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2024-10-10", "series_number": "8033", "volume": "634", "issue": "8033", "pages": "321-327" }, { "id": "authors:78849-p1316", "collection": "authors", "collection_id": "78849-p1316", "cite_using_url": "https://authors.library.caltech.edu/records/78849-p1316", "type": "article", "title": "Benchmarking highly entangled states on a 60-atom analogue quantum simulator", "author": [ { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950" }, { "family_name": "Chen", "given_name": "Zhuo", "orcid": "0000-0002-0789-3687" }, { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751" }, { "family_name": "Mark", "given_name": "Daniel K." }, { "family_name": "Scholl", "given_name": "Pascal" }, { "family_name": "Finkelstein", "given_name": "Ran", "orcid": "0000-0002-4524-5875" }, { "family_name": "Elben", "given_name": "Andreas" }, { "family_name": "Choi", "given_name": "Soonwon", "orcid": "0000-0002-1247-062X", "clpid": "Choi-Soonwon" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Quantum systems have entered a competitive regime in which classical computers must make approximations to represent highly entangled quantum states1,2. However, in this beyond-classically-exact regime, fidelity comparisons between quantum and classical systems have so far been limited to digital quantum devices2,3,4,5, and it remains unsolved how to estimate the actual entanglement content of experiments6. Here, we perform fidelity benchmarking and mixed-state entanglement estimation with a 60-atom analogue Rydberg quantum simulator, reaching a high-entanglement entropy regime in which exact classical simulation becomes impractical. Our benchmarking protocol involves extrapolation from comparisons against an approximate classical algorithm, introduced here, with varying entanglement limits. We then develop and demonstrate an estimator of the experimental mixed-state entanglement6, finding our experiment is competitive with state-of-the-art digital quantum devices performing random circuit evolution2,3,4,5. Finally, we compare the experimental fidelity against that achieved by various approximate classical algorithms, and find that only the algorithm we introduce is able to keep pace with the experiment on the classical hardware we use. Our results enable a new model for evaluating the ability of both analogue and digital quantum devices to generate entanglement in the beyond-classically-exact regime, and highlight the evolving divide between quantum and classical systems.
\nCurrent optical atomic clocks do not utilize their resources optimally. In particular, an exponential gain in sensitivity could be achieved if multiple atomic ensembles were to be controlled or read out individually, even without entanglement. However, controlling optical transitions locally remains an outstanding challenge for neutral-atom-based clocks and quantum computing platforms. Here we show arbitrary, single-site addressing for an optical transition via sub-wavelength controlled moves of atoms trapped in tweezers. The scheme is highly robust as it relies only on the relative position changes of tweezers and requires no additional addressing beams. Using this technique, we implement single-shot, dual-quadrature readout of Ramsey interferometry using two atomic ensembles simultaneously, and show an enhancement of the usable interrogation time at a given phase-slip error probability. Finally, we program a sequence that performs local dynamical decoupling during Ramsey evolution to evolve three ensembles with variable phase sensitivities, a key ingredient of optimal clock interrogation. Our results demonstrate the potential of fully programmable quantum optical clocks even without entanglement and could be combined with metrologically useful entangled states in the future.
\nWe propose and analyze a sample-efficient protocol to estimate the fidelity between an experimentally prepared state and an ideal target state, applicable to a wide class of analog quantum simulators without advanced spatiotemporal control. Our protocol relies on universal fluctuations emerging from generic Hamiltonian dynamics, which we discover in the present work. It does not require fine-tuned control over state preparation, quantum evolution, or readout capability, while achieving near optimal sample complexity: a percent-level precision is obtained with \u223c10\u00b3 measurements, independent of system size. Furthermore, the accuracy of our fidelity estimation improves exponentially with increasing system size. We numerically demonstrate our protocol in a variety of quantum simulator platforms, including quantum gas microscopes, trapped ions, and Rydberg atom arrays. We discuss applications of our method for tasks such as multiparameter estimation of quantum states and processes.
", "doi": "10.1103/physrevlett.131.110601", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2023-09-15", "series_number": "11", "volume": "131", "issue": "11", "pages": "110601" }, { "id": "authors:9zqdg-j6s56", "collection": "authors", "collection_id": "9zqdg-j6s56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230613-730765600.21", "type": "article", "title": "Dark-State Enhanced Loading of an Optical Tweezer Array", "author": [ { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Scholl", "given_name": "Pascal", "orcid": "0000-0002-5675-4237", "clpid": "Scholl-Pascal" }, { "family_name": "Finklestein", "given_name": "Ran", "clpid": "Finklestein-Ran" }, { "family_name": "Madjarov", "given_name": "Ivaylo S.", "clpid": "Madjarov-Ivaylo-S" }, { "family_name": "Grinkemeyer", "given_name": "Brandon", "orcid": "0000-0002-6337-9447", "clpid": "Grinkemeyer-Brandon" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Neutral atoms and molecules trapped in optical tweezers have become a prevalent resource for quantum simulation, computation, and metrology. However, the maximum achievable system sizes of such arrays are often limited by the stochastic nature of loading into optical tweezers, with a typical loading probability of only 50%. Here we present a species-agnostic method for dark-state enhanced loading (DSEL) based on real-time feedback, long-lived shelving states, and iterated array reloading. We demonstrate this technique with a 95-tweezer array of \u2078\u2078Sr atoms, achieving a maximum loading probability of 84.02(4)% and a maximum array size of 91 atoms in one dimension. Our protocol is complementary to, and compatible with, existing schemes for enhanced loading based on direct control over light-assisted collisions, and we predict it can enable close-to-unity filling for arrays of atoms or molecules.", "doi": "10.1103/physrevlett.130.193402", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2023-05-12", "series_number": "19", "volume": "130", "issue": "19", "pages": "Art. No. 193402" }, { "id": "authors:b5z66-8ry73", "collection": "authors", "collection_id": "b5z66-8ry73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230602-251913000.52", "type": "article", "title": "Many-body cavity quantum electrodynamics with driven inhomogeneous emitters", "author": [ { "family_name": "Lei", "given_name": "Mi", "clpid": "Lei-Mi" }, { "family_name": "Fukumori", "given_name": "Rikuto", "orcid": "0000-0003-0896-4261", "clpid": "Fukumori-Rikuto" }, { "family_name": "Rochman", "given_name": "Jake", "clpid": "Rochman-Jake-H" }, { "family_name": "Zhu", "given_name": "Bihui", "orcid": "0000-0002-9457-4560", "clpid": "Zhu-Bihui" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751", "clpid": "Choi-Joonhee" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "abstract": "Quantum emitters coupled to optical resonators are quintessential systems for exploring fundamental phenomena in cavity quantum electrodynamics (cQED) and are commonly used in quantum devices acting as qubits, memories and transducers. Many previous experimental cQED studies have focused on regimes in which a small number of identical emitters interact with a weak external drive such that the system can be described with simple, effective models. However, the dynamics of a disordered, many-body quantum system subject to a strong drive have not been fully explored, despite its importance and potential in quantum applications. Here we study how a large, inhomogeneously broadened ensemble of solid-state emitters coupled with high cooperativity to a nanophotonic resonator behaves under strong excitation. We discover a sharp, collectively induced transparency (CIT) in the cavity reflection spectrum, resulting from quantum interference and collective response induced by the interplay between driven inhomogeneous emitters and cavity photons. Furthermore, coherent excitation within the CIT window leads to highly nonlinear optical emission, spanning from fast superradiance to slow subradiance. These phenomena in the many-body cQED regime enable new mechanisms for achieving slow light and frequency referencing, pave a way towards solid-state superradiant lasers and inform the development of ensemble-based quantum interconnects.", "doi": "10.1038/s41586-023-05884-1", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2023-05-11", "series_number": "7960", "volume": "617", "issue": "7960", "pages": "271-276" }, { "id": "authors:mh73f-6v092", "collection": "authors", "collection_id": "mh73f-6v092", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230227-866489000.2", "type": "article", "title": "Preparing random states and benchmarking with many-body quantum chaos", "author": [ { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751", "clpid": "Choi-Joonhee" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Madjarov", "given_name": "Ivaylo S.", "clpid": "Madjarov-Ivaylo-S" }, { "family_name": "Xie", "given_name": "Xin", "orcid": "0000-0003-4575-6103", "clpid": "Xie-Xin" }, { "family_name": "Finkelstein", "given_name": "Ran", "orcid": "0000-0002-4524-5875", "clpid": "Finkelstein-Ran" }, { "family_name": "Covey", "given_name": "Jacob P.", "orcid": "0000-0001-5104-6883", "clpid": "Covey-Jacob-P" }, { "family_name": "Cotler", "given_name": "Jordan S.", "orcid": "0000-0003-3161-9677", "clpid": "Cotler-Jordan-S" }, { "family_name": "Mark", "given_name": "Daniel K.", "orcid": "0000-0002-5017-5218", "clpid": "Mark-Daniel-K" }, { "family_name": "Huang", "given_name": "Hsin-Yuan", "orcid": "0000-0001-5317-2613", "clpid": "Huang-Hsin-Yuan" }, { "family_name": "Kale", "given_name": "Anant", "orcid": "0000-0002-7049-5630", "clpid": "Kale-Anant" }, { "family_name": "Pichler", "given_name": "Hannes", "orcid": "0000-0003-2144-536X", "clpid": "Pichler-Hannes" }, { "family_name": "Brand\u00e3o", "given_name": "Fernando G. S. L.", "orcid": "0000-0003-3866-9378", "clpid": "Brand\u00e3o-F-G-S-L" }, { "family_name": "Choi", "given_name": "Soonwon", "orcid": "0000-0002-1247-062X", "clpid": "Choi-Soonwon" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Producing quantum states at random has become increasingly important in modern quantum science, with applications being both theoretical and practical. In particular, ensembles of such randomly distributed, but pure, quantum states underlie our understanding of complexity in quantum circuits1 and black holes, and have been used for benchmarking quantum devices in tests of quantum advantage. However, creating random ensembles has necessitated a high degree of spatio-temporal control placing such studies out of reach for a wide class of quantum systems. Here we solve this problem by predicting and experimentally observing the emergence of random state ensembles naturally under time-independent Hamiltonian dynamics, which we use to implement an efficient, widely applicable benchmarking protocol. The observed random ensembles emerge from projective measurements and are intimately linked to universal correlations built up between subsystems of a larger quantum system, offering new insights into quantum thermalization. Predicated on this discovery, we develop a fidelity estimation scheme, which we demonstrate for a Rydberg quantum simulator with up to 25 atoms using fewer than 10\u2074 experimental samples. This method has broad applicability, as we demonstrate for Hamiltonian parameter estimation, target-state generation benchmarking, and comparison of analogue and digital quantum devices. Our work has implications for understanding randomness in quantum dynamics and enables applications of this concept in a much wider context.", "doi": "10.1038/s41586-022-05442-1", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2023-01-19", "series_number": "7944", "volume": "613", "issue": "7944", "pages": "468-473" }, { "id": "authors:k3q2g-m1f50", "collection": "authors", "collection_id": "k3q2g-m1f50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230308-467584400.2", "type": "article", "title": "Emergent Quantum State Designs from Individual Many-Body Wave Functions", "author": [ { "family_name": "Cotler", "given_name": "Jordan S.", "orcid": "0000-0003-3161-9677", "clpid": "Cotler-Jordan-S" }, { "family_name": "Mark", "given_name": "Daniel K.", "orcid": "0000-0002-5017-5218", "clpid": "Mark-Daniel-K" }, { "family_name": "Huang", "given_name": "Hsin-Yuan", "orcid": "0000-0001-5317-2613", "clpid": "Huang-Hsin-Yuan" }, { "family_name": "Hern\u00e1ndez", "given_name": "Felipe", "clpid": "Hern\u00e1ndez-Felipe" }, { "family_name": "Choi", "given_name": "Joonhee", "orcid": "0000-0002-3507-8751", "clpid": "Choi-Joonhee" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Choi", "given_name": "Soonwon", "orcid": "0000-0002-1247-062X", "clpid": "Choi-Soonwon" } ], "abstract": "Quantum chaos in many-body systems provides a bridge between statistical and quantum physics with strong predictive power. This framework is valuable for analyzing properties of complex quantum systems such as energy spectra and the dynamics of thermalization. While contemporary methods in quantum chaos often rely on random ensembles of quantum states and Hamiltonians, this is not reflective of most real-world systems. In this paper, we introduce a new perspective: across a wide range of examples, a single nonrandom quantum state is shown to encode universal and highly random quantum state ensembles. We characterize these ensembles using the notion of quantum state k-designs from quantum information theory and investigate their universality using a combination of analytic and numerical techniques. In particular, we establish that k-designs emerge naturally from generic states in a Hilbert space as well as physical states associated with strongly interacting Hamiltonian dynamics. Our results offer a new approach for studying quantum chaos and provide a practical method for sampling approximately uniformly random states; the latter has wide-ranging applications in quantum information science from tomography to benchmarking.", "doi": "10.1103/prxquantum.4.010311", "issn": "2691-3399", "publisher": "American Physical Society", "publication": "PRX Quantum", "publication_date": "2023-01", "series_number": "1", "volume": "4", "issue": "1", "pages": "Art. No. 010311" }, { "id": "authors:7bhnp-r9z60", "collection": "authors", "collection_id": "7bhnp-r9z60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221031-575177800.11", "type": "article", "title": "Quantum spin liquids bootstrapped from Ising criticality in Rydberg arrays", "author": [ { "family_name": "Slagle", "given_name": "Kevin", "orcid": "0000-0002-8036-3447", "clpid": "Slagle-Kevin" }, { "family_name": "Liu", "given_name": "Yue", "orcid": "0000-0002-5965-0644", "clpid": "Liu-Yue" }, { "family_name": "Aasen", "given_name": "David", "orcid": "0000-0002-6552-488X", "clpid": "Aasen-David" }, { "family_name": "Pichler", "given_name": "Hannes", "orcid": "0000-0003-2144-536X", "clpid": "Pichler-Hannes" }, { "family_name": "Mong", "given_name": "Roger S. K.", "clpid": "Mong-Roger-S-K" }, { "family_name": "Chen", "given_name": "Xie", "orcid": "0000-0003-2215-2497", "clpid": "Chen-Xie" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Alicea", "given_name": "Jason", "orcid": "0000-0001-9979-3423", "clpid": "Alicea-J" } ], "abstract": "Arrays of Rydberg atoms constitute a highly tunable, strongly interacting venue for the pursuit of exotic states of matter. We develop a strategy for accessing a family of fractionalized phases known as quantum spin liquids in two-dimensional Rydberg arrays. We specifically use effective field theory methods to study arrays assembled from Rydberg chains tuned to an Ising phase transition that famously hosts emergent fermions propagating within each chain. This highly entangled starting point allows us to naturally access spin liquids familiar from Kitaev's honeycomb model \u2014 albeit from an entirely different framework. In particular, we argue that finite-range repulsive Rydberg interactions, which frustrate nearby symmetry-breaking orders, can enable coherent propagation of emergent fermions between the chains in which they were born. Delocalization of emergent fermions across the full two-dimensional Rydberg array yields a gapless \u2124\u2082 spin liquid with a single massless Dirac cone. Here, the Rydberg occupation numbers exhibit universal power-law correlations that provide a straightforward experimental diagnostic of this phase. We further show that explicitly breaking symmetries perturbs the gapless spin liquid into gapped, topologically ordered descendants: Breaking lattice symmetries generates toric-code topological order, whereas introducing Floquet-mediated chirality generates non-Abelian Ising topological order. In the toric-code phase, we analytically construct microscopic incarnations of non-Abelian defects, which can be created and transported by dynamically controlling the atom positions in the array. Our work suggests that appropriately tuned Rydberg arrays provide a cold-atoms counterpart of solid-state \"Kitaev materials\" and, more generally, it spotlights a different angle for pursuing experimental platforms for Abelian and non-Abelian fractionalization.", "doi": "10.1103/physrevb.106.115122", "issn": "2469-9950", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2022-09-15", "series_number": "11", "volume": "106", "issue": "11", "pages": "Art. No. 115122" }, { "id": "authors:qn9y0-8j409", "collection": "authors", "collection_id": "qn9y0-8j409", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220601-257666000", "type": "article", "title": "Learning algorithm reflecting universal scaling behavior near phase transitions", "author": [ { "family_name": "Maskara", "given_name": "N.", "orcid": "0000-0001-5775-9542", "clpid": "Maskara-Nishad" }, { "family_name": "Buchhold", "given_name": "M.", "orcid": "0000-0001-5194-9388", "clpid": "Buchhold-Michael" }, { "family_name": "Endres", "given_name": "M.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "van Nieuwenburg", "given_name": "E.", "orcid": "0000-0003-0323-0031", "clpid": "van-Nieuwenburg-Evert-P-L" } ], "abstract": "Machine-learning-inspired techniques have emerged as a new paradigm for analysis of phase transitions in quantum matter. In this work, we introduce a supervised learning algorithm for studying critical phenomena from measurement data, \"neural network scaling,\" which is based on iteratively training convolutional networks of increasing (spatial) complexity and test it on the transverse field Ising chain and q = 6 Potts model. At the continuous Ising transition, our scaling procedure directly reflects the hallmark of a continuous (second-order) phase transition, divergence of a characteristic length scale. Specifically, we extract a classification length scale by measuring the response of the classification accuracy while varying the largest convolution size (architecture of the network). We observe empirically the scaling exponent of the classification length is consistent with a power law with the correlation length exponent \u03bd = 1. Furthermore, we demonstrate the versatility of our algorithm by showing the universal scaling behaviors persist across a variety of measurement bases, including when the order parameter is nonlocal. Finally, we show that the classification length scale remains finite for the q = 6 Potts model, which has a first-order transition and lacks a divergent correlation length.", "doi": "10.1103/physrevresearch.4.l022032", "issn": "2643-1564", "publisher": "American Physical Society", "publication": "Physical Review Research", "publication_date": "2022-05", "series_number": "2", "volume": "4", "issue": "2", "pages": "Art. No. L022032" }, { "id": "authors:bmxdz-db910", "collection": "authors", "collection_id": "bmxdz-db910", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211207-393208000", "type": "article", "title": "Microscopic characterization of Ising conformal field theory in Rydberg chains", "author": [ { "family_name": "Slagle", "given_name": "Kevin", "orcid": "0000-0002-8036-3447", "clpid": "Slagle-Kevin" }, { "family_name": "Aasen", "given_name": "David", "orcid": "0000-0002-6552-488X", "clpid": "Aasen-David" }, { "family_name": "Pichler", "given_name": "Hannes", "orcid": "0000-0003-2144-536X", "clpid": "Pichler-Hannes" }, { "family_name": "Mong", "given_name": "Roger S. K.", "clpid": "Mong-Roger-S-K" }, { "family_name": "Fendley", "given_name": "Paul", "orcid": "0000-0002-7747-0153", "clpid": "Fendley-Paul" }, { "family_name": "Chen", "given_name": "Xie", "orcid": "0000-0003-2215-2497", "clpid": "Chen-Xie" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Alicea", "given_name": "Jason", "orcid": "0000-0001-9979-3423", "clpid": "Alicea-J" } ], "abstract": "Rydberg chains provide an appealing platform for probing conformal field theories (CFTs) that capture universal behavior in a myriad of physical settings. Focusing on a Rydberg chain at the Ising transition separating charge density wave and disordered phases, we establish a detailed link between microscopics and low-energy physics emerging at criticality. We first construct lattice incarnations of primary fields in the underlying Ising CFT including chiral fermions, a nontrivial task given that the Rydberg chain Hamiltonian does not admit an exact fermionization. With this dictionary in hand, we compute correlations of microscopic Rydberg operators, paying special attention to finite, open chains of immediate experimental relevance. We further develop a method to quantify how second-neighbor Rydberg interactions tune the sign and strength of four-fermion couplings in the Ising CFT. Finally, we determine how the Ising fields evolve when four-fermion couplings drive an instability to Ising tricriticality. Our results pave the way to a thorough experimental characterization of Ising criticality in Rydberg arrays, and can inform the design of novel higher-dimensional phases based on coupled critical chains.", "doi": "10.1103/physrevb.104.235109", "issn": "2469-9950", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2021-12-15", "series_number": "23", "volume": "104", "issue": "23", "pages": "Art. No. 235109" }, { "id": "authors:z3bj9-7sx50", "collection": "authors", "collection_id": "z3bj9-7sx50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200312-141649005", "type": "article", "title": "High-Fidelity Control, Detection, and Entanglement of Alkaline-Earth Rydberg Atoms", "author": [ { "family_name": "Madjarov", "given_name": "Ivaylo S.", "clpid": "Madjarov-I-S" }, { "family_name": "Covey", "given_name": "Jacob P.", "orcid": "0000-0001-5104-6883", "clpid": "Covey-J-P" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-A-L" }, { "family_name": "Choi", "given_name": "Joonhee", "clpid": "Choi-Joonhee" }, { "family_name": "Kale", "given_name": "Anant", "orcid": "0000-0002-7049-5630", "clpid": "Kale-Anant" }, { "family_name": "Cooper", "given_name": "Alexandre", "orcid": "0000-0002-8759-9647", "clpid": "Cooper-Alexandre" }, { "family_name": "Pichler", "given_name": "Hannes", "clpid": "Pichler-H" }, { "family_name": "Schkolnik", "given_name": "Vladimir", "orcid": "0000-0002-2902-5549", "clpid": "Schkolnik-V" }, { "family_name": "Williams", "given_name": "Jason R.", "clpid": "Williams-J-R" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Trapped neutral atoms have become a prominent platform for quantum science, where entanglement fidelity records have been set using highly excited Rydberg states. However, controlled two-qubit entanglement generation has so far been limited to alkali species, leaving the exploitation of more complex electronic structures as an open frontier that could lead to improved fidelities and fundamentally different applications such as quantum-enhanced optical clocks. Here, we demonstrate a novel approach utilizing the two-valence electron structure of individual alkaline-earth Rydberg atoms. We find fidelities for Rydberg state detection, single-atom Rabi operations and two-atom entanglement that surpass previously published values. Our results pave the way for novel applications, including programmable quantum metrology and hybrid atom\u2013ion systems, and set the stage for alkaline-earth based quantum computing architectures.", "doi": "10.1038/s41567-020-0903-z", "issn": "1745-2473", "publisher": "Nature Publishing Group", "publication": "Nature Physics", "publication_date": "2020-08", "series_number": "8", "volume": "16", "issue": "8", "pages": "857-861" }, { "id": "authors:3rmja-0yv46", "collection": "authors", "collection_id": "3rmja-0yv46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190809-100641765", "type": "article", "title": "Integrating Neural Networks with a Quantum Simulator for State Reconstruction", "author": [ { "family_name": "Torlai", "given_name": "Giacomo", "orcid": "0000-0001-8478-4436", "clpid": "Torlai-G" }, { "family_name": "Timar", "given_name": "Brian", "clpid": "Timar-B" }, { "family_name": "van Nieuwenburg", "given_name": "Evert P. L.", "orcid": "0000-0003-0323-0031", "clpid": "van-Nieuwenburg-E-P-L" }, { "family_name": "Levine", "given_name": "Harry", "clpid": "Levine-H" }, { "family_name": "Omran", "given_name": "Ahmed", "orcid": "0000-0002-2253-0278", "clpid": "Omran-A" }, { "family_name": "Keesling", "given_name": "Alexander", "orcid": "0000-0003-3931-0949", "clpid": "Keesling-A" }, { "family_name": "Bernien", "given_name": "Hannes", "clpid": "Bernien-H" }, { "family_name": "Greiner", "given_name": "Markus", "orcid": "0000-0002-2935-2363", "clpid": "Greiner-M" }, { "family_name": "Vuleti\u0107", "given_name": "Vladan", "clpid": "Vuleti\u0107-V" }, { "family_name": "Lukin", "given_name": "Mikhail D.", "orcid": "0000-0002-8658-1007", "clpid": "Lukin-M-D" }, { "family_name": "Melko", "given_name": "Roger G.", "orcid": "0000-0002-5505-8176", "clpid": "Melko-R-G" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "We demonstrate quantum many-body state reconstruction from experimental data generated by a programmable quantum simulator by means of a neural-network model incorporating known experimental errors. Specifically, we extract restricted Boltzmann machine wave functions from data produced by a Rydberg quantum simulator with eight and nine atoms in a single measurement basis and apply a novel regularization technique to mitigate the effects of measurement errors in the training data. Reconstructions of modest complexity are able to capture one- and two-body observables not accessible to experimentalists, as well as more sophisticated observables such as the R\u00e9nyi mutual information. Our results open the door to integration of machine learning architectures with intermediate-scale quantum hardware.", "doi": "10.1103/PhysRevLett.123.230504", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2019-12-06", "series_number": "23", "volume": "123", "issue": "23", "pages": "Art. No. 230504" }, { "id": "authors:t8b67-x6g28", "collection": "authors", "collection_id": "t8b67-x6g28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191022-085737494", "type": "article", "title": "An atomic array optical clock with single-atom readout", "author": [ { "family_name": "Madjarov", "given_name": "Ivaylo S.", "clpid": "Madjarov-Ivaylo-S" }, { "family_name": "Cooper", "given_name": "Alexandre", "orcid": "0000-0002-8759-9647", "clpid": "Cooper-Alexandre" }, { "family_name": "Shaw", "given_name": "Adam L.", "orcid": "0000-0002-8059-5950", "clpid": "Shaw-Adam-L" }, { "family_name": "Covey", "given_name": "Jacob P.", "orcid": "0000-0001-5104-6883", "clpid": "Covey-Jacob-P" }, { "family_name": "Schkolnik", "given_name": "Vladimir", "clpid": "Schkolnik-Vladimir" }, { "family_name": "Yoon", "given_name": "Tai Hyun", "clpid": "Yoon-Tai-Hyun" }, { "family_name": "Williams", "given_name": "Jason R.", "clpid": "Williams-Jason-R" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Currently, the most accurate and stable clocks use optical interrogation of either a single ion or an ensemble of neutral atoms confined in an optical lattice. Here, we demonstrate a new optical clock system based on an array of individually trapped neutral atoms with single-atom readout, merging many of the benefits of ion and lattice clocks as well as creating a bridge to recently developed techniques in quantum simulation and computing with neutral atoms. We evaluate single-site resolved frequency shifts and short-term stability via self-comparison. Atom-by-atom feedback control enables direct experimental estimation of laser noise contributions. Results agree well with an ab initio Monte Carlo simulation that incorporates finite temperature, projective read-out, laser noise, and feedback dynamics. Our approach, based on a tweezer array, also suppresses interaction shifts while retaining a short dead time, all in a comparatively simple experimental setup. These results establish the foundations for a third optical clock platform suited to advance stationary and transportable clock systems, while providing a novel starting point for entanglement-enhanced metrology and quantum clock networks as well as applications in quantum computing and communication with individual neutral atoms requiring optical clock state control.", "doi": "10.1103/PhysRevX.9.041052", "issn": "2160-3308", "publisher": "American Physical Society", "publication": "Physical Review X", "publication_date": "2019-10", "series_number": "4", "volume": "9", "issue": "4", "pages": "Art. No. 041052" }, { "id": "authors:cag7z-th930", "collection": "authors", "collection_id": "cag7z-th930", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190808-135256638", "type": "article", "title": "Generation and manipulation of Schr\u00f6dinger cat states in Rydberg atom arrays", "author": [ { "family_name": "Omran", "given_name": "A.", "orcid": "0000-0002-2253-0278", "clpid": "Omran-A" }, { "family_name": "Levine", "given_name": "H.", "clpid": "Levine-H" }, { "family_name": "Keesling", "given_name": "A.", "orcid": "0000-0003-3931-0949", "clpid": "Keesling-A" }, { "family_name": "Semeghini", "given_name": "G.", "clpid": "Semeghini-G" }, { "family_name": "Wang", "given_name": "T. T.", "clpid": "Wang-Tout-T" }, { "family_name": "Ebadi", "given_name": "S.", "clpid": "Ebadi-S" }, { "family_name": "Bernien", "given_name": "H.", "clpid": "Bernien-H" }, { "family_name": "Zibrov", "given_name": "A. S.", "orcid": "0000-0002-3200-4351", "clpid": "Zibrov-A-S" }, { "family_name": "Pichler", "given_name": "H.", "clpid": "Pichler-H" }, { "family_name": "Choi", "given_name": "S.", "clpid": "Choi-Soonwon" }, { "family_name": "Cui", "given_name": "J.", "clpid": "Cui-Jian" }, { "family_name": "Rossignolo", "given_name": "M.", "clpid": "Rossignolo-M" }, { "family_name": "Rembold", "given_name": "P.", "clpid": "Rembold-P" }, { "family_name": "Montangero", "given_name": "S.", "clpid": "Montangero-S" }, { "family_name": "Calarco", "given_name": "T.", "clpid": "Calarco-T" }, { "family_name": "Endres", "given_name": "M.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Greiner", "given_name": "M.", "orcid": "0000-0002-2935-2363", "clpid": "Greiner-M" }, { "family_name": "Vuleti\u0107", "given_name": "V.", "clpid": "Vuleti\u0107-V" }, { "family_name": "Lukin", "given_name": "M. D.", "orcid": "0000-0002-8658-1007", "clpid": "Lukin-M-D" } ], "abstract": "Quantum entanglement involving coherent superpositions of macroscopically distinct states is among the most striking features of quantum theory, but its realization is challenging because such states are extremely fragile. Using a programmable quantum simulator based on neutral atom arrays with interactions mediated by Rydberg states, we demonstrate the creation of \"Schr\u00f6dinger cat\" states of the Greenberger-Horne-Zeilinger (GHZ) type with up to 20 qubits. Our approach is based on engineering the energy spectrum and using optimal control of the many-body system. We further demonstrate entanglement manipulation by using GHZ states to distribute entanglement to distant sites in the array, establishing important ingredients for quantum information processing and quantum metrology.", "doi": "10.1126/science.aax9743", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2019-08-09", "series_number": "6453", "volume": "365", "issue": "6453", "pages": "570-574" }, { "id": "authors:ymyg9-61358", "collection": "authors", "collection_id": "ymyg9-61358", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190123-112141969", "type": "article", "title": "2000-times repeated imaging of strontium atoms in clock-magic tweezer arrays", "author": [ { "family_name": "Covey", "given_name": "Jacob P.", "orcid": "0000-0001-5104-6883", "clpid": "Covey-J-P" }, { "family_name": "Madjarov", "given_name": "Ivaylo S.", "clpid": "Madjarov-I-S" }, { "family_name": "Cooper", "given_name": "Alexandre", "orcid": "0000-0002-8759-9647", "clpid": "Cooper-Alexandre" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "We demonstrate single-atom resolved imaging with a survival probability of 0.99932(8) and a fidelity of 0.99991(1), enabling us to perform repeated high-fidelity imaging of single atoms in tweezers for thousands of times. We further observe lifetimes under laser cooling of more than seven minutes, an order of magnitude longer than in previous tweezer studies. Experiments are performed with strontium atoms in 813.4 nm tweezer arrays, which is at a magic wavelength for the clock transition. Tuning to this wavelength is enabled by off-magic Sisyphus cooling on the intercombination line, which lets us choose the tweezer wavelength almost arbitrarily. We find that a single not retro-reflected cooling beam in the radial direction is sufficient for mitigating recoil heating during imaging. Moreover, this cooling technique yields temperatures below 5 \u03bcK, as measured by release and recapture. Finally, we demonstrate clock-state resolved detection with average survival probability of 0.996(1) and average state detection fidelity of 0.981(1). Our work paves the way for atom-by-atom assembly of large defect-free arrays of alkaline-earth atoms, in which repeated interrogation of the clock transition is an imminent possibility.", "doi": "10.1103/PhysRevLett.122.173201", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2019-05-03", "series_number": "17", "volume": "122", "issue": "17", "pages": "Art. No. 173201" }, { "id": "authors:xye6z-7bh16", "collection": "authors", "collection_id": "xye6z-7bh16", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190123-110710682", "type": "article", "title": "Quantum Kibble\u2013Zurek mechanism and critical dynamics on a programmable Rydberg simulator", "author": [ { "family_name": "Keesling", "given_name": "Alexander", "orcid": "0000-0003-3931-0949", "clpid": "Keesling-A" }, { "family_name": "Omran", "given_name": "Ahmed", "orcid": "0000-0002-2253-0278", "clpid": "Omran-A" }, { "family_name": "Levine", "given_name": "Harry", "clpid": "Levine-H" }, { "family_name": "Bernien", "given_name": "Hannes", "clpid": "Bernien-H" }, { "family_name": "Pichler", "given_name": "Hannes", "clpid": "Pichler-H" }, { "family_name": "Choi", "given_name": "Soonwon", "clpid": "Choi-Soonwon" }, { "family_name": "Samajdar", "given_name": "Rhine", "clpid": "Samajdar-R" }, { "family_name": "Schwartz", "given_name": "Sylvain", "clpid": "Schwartz-S" }, { "family_name": "Silvi", "given_name": "Pietro", "clpid": "Silvi-P" }, { "family_name": "Sachdev", "given_name": "Subir", "orcid": "0000-0002-2432-7070", "clpid": "Sachdev-S" }, { "family_name": "Zoller", "given_name": "Peter", "clpid": "Zoller-P" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Greiner", "given_name": "Markus", "orcid": "0000-0002-2935-2363", "clpid": "Greiner-M" }, { "family_name": "Vuleti\u0107", "given_name": "Vladan", "clpid": "Vuleti\u0107-V" }, { "family_name": "Lukin", "given_name": "Mikhail D.", "orcid": "0000-0002-8658-1007", "clpid": "Lukin-M-D" } ], "abstract": "Quantum phase transitions (QPTs) involve transformations between different states of matter that are driven by quantum fluctuations1. These fluctuations play a dominant part in the quantum critical region surrounding the transition point, where the dynamics is governed by the universal properties associated with the QPT. Although time-dependent phenomena associated with classical, thermally driven phase transitions have been extensively studied in systems ranging from the early Universe to Bose\u2013Einstein condensates, understanding critical real-time dynamics in isolated, non-equilibrium quantum systems remains a challenge. Here we use a Rydberg atom quantum simulator with programmable interactions to study the quantum critical dynamics associated with several distinct QPTs. By studying the growth of spatial correlations when crossing the QPT, we experimentally verify the quantum Kibble\u2013Zurek mechanism (QKZM) for an Ising-type QPT, explore scaling universality and observe corrections beyond QKZM predictions. This approach is subsequently used to measure the critical exponents associated with chiral clock models, providing new insights into exotic systems that were not previously understood and opening the door to precision studies of critical phenomena, simulations of lattice gauge theories and applications to quantum optimization.", "doi": "10.1038/s41586-019-1070-1", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2019-04-11", "series_number": "7751", "volume": "568", "issue": "7751", "pages": "207-211" }, { "id": "authors:9cm35-zft84", "collection": "authors", "collection_id": "9cm35-zft84", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181203-111424788", "type": "article", "title": "Telecom-band quantum optics with ytterbium atoms and silicon\n nanophotonics", "author": [ { "family_name": "Covey", "given_name": "Jacob P.", "orcid": "0000-0001-5104-6883", "clpid": "Covey-J-P" }, { "family_name": "Sipahigil", "given_name": "Alp", "orcid": "0000-0003-1469-5272", "clpid": "Sipahigil-A" }, { "family_name": "Szoke", "given_name": "Szilard", "clpid": "Szoke-S" }, { "family_name": "Sinclair", "given_name": "Neil", "clpid": "Sinclair-N" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Painter", "given_name": "Oskar", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" } ], "abstract": "Wavelengths in the telecommunication window (approximately 1.25\u20131.65 \u03bcm) are ideal for quantum communication due to low transmission loss in fiber networks. To realize quantum networks operating at these wavelengths, long-lived quantum memories that couple to telecom-band photons with high efficiency need to be developed. We propose coupling neutral ytterbium atoms, which have a strong telecom-wavelength transition, to a silicon photonic crystal cavity. Specifically, we consider the ^3P_0\u2194^3D_1 transition in neutral ^(171)Yb to interface its long-lived nuclear spin in the metastable ^3P_0 \"clock\" state with a telecom-band photon at 1.4\u03bcm. We show that Yb atoms can be trapped using a short-wavelength (approximately 470 nm) tweezer at a distance of 350 nm from the silicon photonic crystal cavity. At this distance, due to the slowly decaying evanescent cavity field at a longer wavelength, we obtain a single-photon Rabi frequency of g/2\u03c0 \u2248 100 MHz and a cooperativity of C \u2248 47 while maintaining a high photon collection efficiency into a single mode fiber. The combination of high system efficiency, telecom-band operation, and long coherence times makes this platform well suited for quantum optics on a silicon chip and long-distance quantum communication.", "doi": "10.1103/PhysRevApplied.11.034044", "issn": "2331-7019", "publisher": "American Physical Society", "publication": "Physical Review Applied", "publication_date": "2019-03", "series_number": "3", "volume": "11", "issue": "3", "pages": "Art. No. 034044" }, { "id": "authors:p6cqp-yqz26", "collection": "authors", "collection_id": "p6cqp-yqz26", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181203-104933854", "type": "article", "title": "Alkaline earth atoms in optical tweezers", "author": [ { "family_name": "Cooper", "given_name": "Alexandre", "orcid": "0000-0002-8759-9647", "clpid": "Cooper-Alexandre" }, { "family_name": "Covey", "given_name": "Jacob P.", "orcid": "0000-0001-5104-6883", "clpid": "Covey-J-P" }, { "family_name": "Madjarov", "given_name": "Ivaylo S.", "clpid": "Madjarov-I-S" }, { "family_name": "Porsev", "given_name": "Sergey G.", "orcid": "0000-0003-0417-2726", "clpid": "Porsev-S-G" }, { "family_name": "Safronova", "given_name": "Marianna S.", "orcid": "0000-0002-1305-4011", "clpid": "Safronova-M-S" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "We demonstrate single-shot imaging and narrow-line cooling of individual alkaline-earth atoms in optical tweezers; specifically, strontium trapped in 515.2\u2212nm light. Our approach enables high-fidelity detection of single atoms by imaging photons from the broad singlet transition while cooling on the narrow intercombination line, and we extend this technique to highly uniform two-dimensional tweezer arrays with 121 sites. Cooling during imaging is based on a previously unobserved narrow-line Sisyphus mechanism, which we predict to be applicable in a wide variety of experimental situations. Further, we demonstrate optically resolved sideband cooling of a single atom to near the motional ground state of a tweezer, which is tuned to a magic-trapping configuration achieved by elliptical polarization. Finally, we present calculations, in agreement with our experimental results, that predict a linear-polarization and polarization-independent magic crossing at 520(2) nm and 500.65(50) nm, respectively. Our results pave the way for a wide range of novel experimental avenues based on individually controlled alkaline-earth atoms in tweezers\u2014from fundamental experiments in atomic physics to quantum computing, simulation, and metrology.", "doi": "10.1103/PhysRevX.8.041055", "issn": "2160-3308", "publisher": "American Physical Society", "publication": "Physical Review X", "publication_date": "2018-10", "series_number": "4", "volume": "8", "issue": "4", "pages": "Art. No. 041055" }, { "id": "authors:94btx-2ez81", "collection": "authors", "collection_id": "94btx-2ez81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180620-191317491", "type": "article", "title": "High-fidelity control and entanglement of Rydberg atom qubits", "author": [ { "family_name": "Levine", "given_name": "Harry", "clpid": "Levine-H" }, { "family_name": "Keesling", "given_name": "Alexander", "orcid": "0000-0003-3931-0949", "clpid": "Keesling-A" }, { "family_name": "Omran", "given_name": "Ahmed", "orcid": "0000-0002-2253-0278", "clpid": "Omran-A" }, { "family_name": "Bernien", "given_name": "Hannes", "clpid": "Bernien-H" }, { "family_name": "Schwartz", "given_name": "Sylvain", "clpid": "Schwartz-S" }, { "family_name": "Zibrov", "given_name": "Alexander S.", "orcid": "0000-0002-3200-4351", "clpid": "Zibrov-A-S" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Greiner", "given_name": "Markus", "orcid": "0000-0002-2935-2363", "clpid": "Greiner-M" }, { "family_name": "Vuleti\u0107", "given_name": "Vladan", "clpid": "Vuleti\u0107-V" }, { "family_name": "Lukin", "given_name": "Mikhail D.", "orcid": "0000-0002-8658-1007", "clpid": "Lukin-M-D" } ], "abstract": "Individual neutral atoms excited to Rydberg states are a promising platform for quantum simulation and quantum information processing. However, experimental progress to date has been limited by short coherence times and relatively low gate fidelities associated with such Rydberg excitations. We report progress towards high-fidelity quantum control of Rydberg-atom qubits. Enabled by a reduction in laser phase noise, our approach yields a significant improvement in coherence properties of individual qubits. We further show that this high-fidelity control extends to the multi-particle case by preparing a two-atom entangled state with a fidelity exceeding 0.97(3), and extending its lifetime with a two-atom dynamical decoupling protocol. These advances open up new prospects for scalable quantum simulation and quantum computation with neutral atoms.", "doi": "10.1103/PhysRevLett.121.123603", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2018-09-21", "series_number": "12", "volume": "121", "issue": "12", "pages": "Art. No. 123603" }, { "id": "authors:bnmf7-v2737", "collection": "authors", "collection_id": "bnmf7-v2737", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180521-092304073", "type": "article", "title": "Berry electrodynamics: Anomalous drift and pumping from a time-dependent Berry connection", "author": [ { "family_name": "Chaudhary", "given_name": "Swati", "clpid": "Chaudhary-Swati" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Refael", "given_name": "Gil", "clpid": "Refael-G" } ], "abstract": "The Berry curvature of a Bloch band can be interpreted as a local magnetic field in reciprocal space. This analogy can be extended by defining an electric field analog in reciprocal space which arises from the time-dependent Berry connection. We explore the term in the semiclassical equation of motion that gives rise to this phenomenon, and show that it can lead to anomalous drift in wave-packet motion. A similar effect arises from changes in the band population due to periodic driving, where the resulting drift depends on the nature of the drive and can be expressed in terms of a shift vector. Finally, these effects can be combined to build a pump with a net anomalous drift during a cyclic evolution in momentum space.", "doi": "10.1103/PhysRevB.98.064310", "issn": "2469-9950", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2018-08-01", "series_number": "6", "volume": "98", "issue": "6", "pages": "Art. No. 064310" }, { "id": "authors:hejg6-57263", "collection": "authors", "collection_id": "hejg6-57263", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170921-114357507", "type": "article", "title": "Probing many-body dynamics on a 51-atom quantum simulator", "author": [ { "family_name": "Bernien", "given_name": "Hannes", "clpid": "Bernien-H" }, { "family_name": "Schwartz", "given_name": "Sylvain", "clpid": "Schwartz-S" }, { "family_name": "Keesling", "given_name": "Alexander", "orcid": "0000-0003-3931-0949", "clpid": "Keesling-A" }, { "family_name": "Levine", "given_name": "Harry", "clpid": "Levine-H" }, { "family_name": "Omran", "given_name": "Ahmed", "orcid": "0000-0002-2253-0278", "clpid": "Omran-A" }, { "family_name": "Pichler", "given_name": "Hannes", "clpid": "Pichler-H" }, { "family_name": "Choi", "given_name": "Soonwon", "clpid": "Choi-Soonwon" }, { "family_name": "Zibrov", "given_name": "Alexander S.", "orcid": "0000-0002-3200-4351", "clpid": "Zibrov-A-S" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Greiner", "given_name": "Markus", "orcid": "0000-0002-2935-2363", "clpid": "Greiner-M" }, { "family_name": "Vuleti\u0107", "given_name": "Vladan", "clpid": "Vuleti\u0107-V" }, { "family_name": "Lukin", "given_name": "Mikhail D.", "orcid": "0000-0002-8658-1007", "clpid": "Lukin-M-D" } ], "abstract": "Controllable, coherent many-body systems can provide insights into the fundamental properties of quantum matter, enable the realization of new quantum phases and could ultimately lead to computational systems that outperform existing computers based on classical approaches. Here we demonstrate a method for creating controlled many-body quantum matter that combines deterministically prepared, reconfigurable arrays of individually trapped cold atoms with strong, coherent interactions enabled by excitation to Rydberg states. We realize a programmable Ising-type quantum spin model with tunable interactions and system sizes of up to 51 qubits. Within this model, we observe phase transitions into spatially ordered states that break various discrete symmetries, verify the high-fidelity preparation of these states and investigate the dynamics across the phase transition in large arrays of atoms. In particular, we observe robust many-body dynamics corresponding to persistent oscillations of the order after a rapid quantum quench that results from a sudden transition across the phase boundary. Our method provides a way of exploring many-body phenomena on a programmable quantum simulator and could enable realizations of new quantum algorithms.", "doi": "10.1038/nature24622", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2017-11-30", "series_number": "7682", "volume": "551", "issue": "7682", "pages": "579-584" }, { "id": "authors:ehk7g-cgm69", "collection": "authors", "collection_id": "ehk7g-cgm69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170602-091316600", "type": "article", "title": "Scrambling and thermalization in a diffusive quantum many-body system", "author": [ { "family_name": "Bohrdt", "given_name": "A.", "clpid": "Bohrdt-A" }, { "family_name": "Mendl", "given_name": "C. B.", "orcid": "0000-0002-6386-0230", "clpid": "Mendl-C-B" }, { "family_name": "Endres", "given_name": "M.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Knap", "given_name": "M.", "clpid": "Knap-M" } ], "abstract": "Out-of-time ordered (OTO) correlation functions describe scrambling of information in correlated quantum matter. They are of particular interest in incoherent quantum systems lacking well defined quasi-particles. Thus far, it is largely elusive how OTO correlators spread in incoherent systems with diffusive transport governed by a few globally conserved quantities. Here, we study the dynamical response of such a system using high-performance matrix-product-operator techniques. Specifically, we consider the non-integrable, one-dimensional Bose\u2013Hubbard model in the incoherent high-temperature regime. Our system exhibits diffusive dynamics in time-ordered correlators of globally conserved quantities, whereas OTO correlators display a ballistic, light-cone spreading of quantum information. The slowest process in the global thermalization of the system is thus diffusive, yet information spreading is not inhibited by such slow dynamics. We furthermore develop an experimentally feasible protocol to overcome some challenges faced by existing proposals and to probe time-ordered and OTO correlation functions. Our study opens new avenues for both the theoretical and experimental exploration of thermalization and information scrambling dynamics.", "doi": "10.1088/1367-2630/aa719b", "issn": "1367-2630", "publisher": "IOP", "publication": "New Journal of Physics", "publication_date": "2017-06", "series_number": "6", "volume": "19", "issue": "6", "pages": "Art. No. 063001" }, { "id": "authors:m6g2t-qyz70", "collection": "authors", "collection_id": "m6g2t-qyz70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161004-102552364", "type": "article", "title": "Atom-by-atom assembly of defect-free one-dimensional cold atom arrays", "author": [ { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Bernien", "given_name": "Hannes", "clpid": "Bernien-H" }, { "family_name": "Keesling", "given_name": "Alexander", "orcid": "0000-0003-3931-0949", "clpid": "Keesling-A" }, { "family_name": "Levine", "given_name": "Harry", "clpid": "Levine-H" }, { "family_name": "Anschuetz", "given_name": "Eric R.", "clpid": "Anschuetz-E-R" }, { "family_name": "Krajenbrink", "given_name": "Alexandre", "clpid": "Krajenbrink-A" }, { "family_name": "Senko", "given_name": "Crystal", "clpid": "Senko-Crystal" }, { "family_name": "Vuleti\u0107", "given_name": "Vladan", "clpid": "Vuleti\u0107-V" }, { "family_name": "Greiner", "given_name": "Markus", "orcid": "0000-0002-2935-2363", "clpid": "Greiner-M" }, { "family_name": "Lukin", "given_name": "Mikhail D.", "orcid": "0000-0002-8658-1007", "clpid": "Lukin-M-D" } ], "abstract": "The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a platform for the deterministic preparation of regular one-dimensional arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of over 50 atoms in less than 400 milliseconds. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach may enable controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.", "doi": "10.1126/science.aah3752", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2016-11-25", "series_number": "6315", "volume": "354", "issue": "6315", "pages": "1024-1027" }, { "id": "authors:kn2st-f3a65", "collection": "authors", "collection_id": "kn2st-f3a65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160526-132227087", "type": "article", "title": "Destruction of string order after a quantum quench", "author": [ { "family_name": "Calvanese Strinati", "given_name": "Marcello", "clpid": "Calvanese-Strinati-M" }, { "family_name": "Mazza", "given_name": "Leonardo", "clpid": "Mazza-L" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Rossini", "given_name": "Davide", "clpid": "Rossini-D" }, { "family_name": "Fazio", "given_name": "Rosario", "clpid": "Fazio-R" } ], "abstract": "We investigate the evolution of string order in a spin-1 chain following a quantum quench. After initializing the chain in the Affleck-Kennedy-Lieb-Tasaki state, we analyze in detail how string order evolves as a function of time at different length scales. The Hamiltonian after the quench is chosen either to preserve or to suddenly break the symmetry which ensures the presence of string order. Depending on which of these two situations arises, string order is either preserved or lost even at infinitesimal times in the thermodynamic limit. The fact that nonlocal order may be abruptly destroyed, what we call string-order melting, makes it qualitatively different from typical order parameters in the manner of Landau. This situation is thoroughly characterized by means of numerical simulations based on matrix product states algorithms and analytical studies based on a short-time expansion for several simplified models.", "doi": "10.1103/PhysRevB.94.024302", "issn": "1098-0121", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2016-07", "series_number": "2", "volume": "94", "issue": "2", "pages": "Art. No. 024302" }, { "id": "authors:bs2dr-78f23", "collection": "authors", "collection_id": "bs2dr-78f23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160526-131417294", "type": "article", "title": "Bloch state tomography using Wilson lines", "author": [ { "family_name": "Li", "given_name": "Tracy", "clpid": "Li-Tracy" }, { "family_name": "Duca", "given_name": "Lucia", "clpid": "Duca-L" }, { "family_name": "Reitter", "given_name": "Martin", "clpid": "Reitter-M" }, { "family_name": "Grusdt", "given_name": "Fabian", "clpid": "Grusdt-F" }, { "family_name": "Demler", "given_name": "Eugene", "clpid": "Demler-E-A" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Schleier-Smith", "given_name": "Monika", "clpid": "Schleier-Smith-M" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Schneider", "given_name": "Ulrich", "clpid": "Schneider-U" } ], "abstract": "Topology and geometry are essential to our understanding of modern physics, underlying many foundational concepts from high-energy theories, quantum information, and condensed-matter physics. In condensed-matter systems, a wide range of phenomena stem from the geometry of the band eigenstates, which is encoded in the matrix-valued Wilson line for general multiband systems. Using an ultracold gas of rubidium atoms loaded in a honeycomb optical lattice, we realize strong-force dynamics in Bloch bands that are described by Wilson lines and observe an evolution in the band populations that directly reveals the band geometry. Our technique enables a full determination of band eigenstates, Berry curvature, and topological invariants, including single- and multiband Chern and Z_2 numbers.", "doi": "10.1126/science.aad5812", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2016-05-27", "series_number": "6289", "volume": "352", "issue": "6289", "pages": "1094-1097" }, { "id": "authors:avk2j-7ya96", "collection": "authors", "collection_id": "avk2j-7ya96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160104-160827699", "type": "article", "title": "Landau Levels in Strained Optical Lattices", "author": [ { "family_name": "Tian", "given_name": "Binbin", "clpid": "Tian-Binbin" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Pekker", "given_name": "David", "clpid": "Pekker-D" } ], "abstract": "We propose a hexagonal optical lattice system with spatial variations in the hopping matrix elements. Just like in the valley Hall effect in strained graphene, for atoms near the Dirac points the variations in the hopping matrix elements can be described by a pseudomagnetic field and result in the formation of Landau levels. We show that the pseudomagnetic field leads to measurable experimental signatures in momentum resolved Bragg spectroscopy, Bloch oscillations, cyclotron motion, and quantization of in situ densities. Our proposal can be realized by a slight modification of existing experiments. In contrast to previous methods, pseudomagnetic fields are realized in a completely static system avoiding common heating effects and therefore opening the door to studying interaction effects in Landau levels with cold atoms.", "doi": "10.1103/PhysRevLett.115.236803", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2015-12-04", "series_number": "23", "volume": "115", "issue": "23", "pages": "Art. No. 236803" }, { "id": "authors:aktx8-g3n35", "collection": "authors", "collection_id": "aktx8-g3n35", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151207-095321750", "type": "article", "title": "Massive Goldstone (Higgs) mode in two-dimensional ultracold atomic lattice systems", "author": [ { "family_name": "Liu", "given_name": "Longxiang", "clpid": "Liu-Longxiang" }, { "family_name": "Chen", "given_name": "Kun", "clpid": "Chen-Kun" }, { "family_name": "Deng", "given_name": "Youjin", "clpid": "Deng-Youjin" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Pollet", "given_name": "Lode", "clpid": "Pollet-L" }, { "family_name": "Prokof'ev", "given_name": "Nikolay", "clpid": "Prokof'ev-N-V" } ], "abstract": "We discuss how to reveal the massive Goldstone mode, often referred to as the Higgs amplitude mode, near the superfluid-to-insulator quantum critical point (QCP) in a system of two-dimensional ultracold bosonic atoms in optical lattices. The spectral function of the amplitude response is obtained by analytic continuation of the kinetic energy correlation function calculated by Monte Carlo methods. Our results enable a direct comparison with the recent experiment [M. Endres, T. Fukuhara, D. Pekker, M. Cheneau, P. Schau\u00df, C. Gross, E. Demler, S. Kuhr, and I. Bloch, Nature (London) 487, 454 (2012)] and demonstrate a good agreement for temperature shifts induced by lattice modulation. Based on our numerical analysis, we formulate the necessary conditions in terms of homogeneity, detuning from the QCP and temperature in order to reveal the massive Goldstone resonance peak in spectral functions experimentally. We also propose to apply a local modulation at the trap center to overcome the inhomogeneous broadening caused by the parabolic trap confinement.", "doi": "10.1103/PhysRevB.92.174521", "issn": "1098-0121", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2015-11-01", "series_number": "17", "volume": "92", "issue": "17", "pages": "Art. No. 174521" }, { "id": "authors:e9vn3-1r738", "collection": "authors", "collection_id": "e9vn3-1r738", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-090455950", "type": "article", "title": "Spatially Resolved Detection of a Spin-Entanglement Wave in a Bose-Hubbard Chain", "author": [ { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Hild", "given_name": "Sebastian", "clpid": "Hild-S" }, { "family_name": "Zeiher", "given_name": "Johannes", "clpid": "Zeiher-J" }, { "family_name": "Schau\u00df", "given_name": "Peter", "clpid": "Schau\u00df-P" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Gross", "given_name": "Christian", "clpid": "Gross-C" } ], "abstract": "Entanglement is an essential property of quantum many-body systems. However, its local detection is challenging and was so far limited to spin degrees of freedom in ion chains. Here we measure entanglement between the spins of atoms located on two lattice sites in a one-dimensional Bose-Hubbard chain which features both local spin- and particle-number fluctuations. Starting with an initially localized spin impurity, we observe an outwards propagating entanglement wave and show quantitatively how entanglement in the spin sector rapidly decreases with increasing particle-number fluctuations in the chain.", "doi": "10.1103/PhysRevLett.115.035302", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2015-07-17", "series_number": "3", "volume": "115", "issue": "3", "pages": "Art. No. 035302" }, { "id": "authors:mh3b8-3gd79", "collection": "authors", "collection_id": "mh3b8-3gd79", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-072507810", "type": "article", "title": "Quantum simulation: Choose your own interaction", "author": [ { "family_name": "Thompson", "given_name": "Jeff", "clpid": "Thompson-J-R" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "Quantum many-body physics can now be studied experimentally using a variety of methods from atomic and optical physics, such as ultracold atoms, chains of trapped ions or superconducting circuits. The ultimate goal in this field, known as quantum simulation, is to realize well-controlled model systems in regimes that are difficult to understand through analytical and numerical approaches. Typically, this is the case for strongly interacting systems, and consequently the engineering of interactions is at the heart of quantum simulation.", "doi": "10.1038/nphoton.2015.62", "issn": "1749-4885", "publisher": "Nature Publishing Group", "publication": "Nature Photonics", "publication_date": "2015-05", "series_number": "5", "volume": "9", "issue": "5", "pages": "285-287" }, { "id": "authors:6d687-7v403", "collection": "authors", "collection_id": "6d687-7v403", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-085233241", "type": "article", "title": "Detecting two-site spin-entanglement in many-body systems with local particle-number fluctuations", "author": [ { "family_name": "Mazza", "given_name": "Leonardo", "clpid": "Mazza-L" }, { "family_name": "Rossini", "given_name": "Davide", "clpid": "Rossini-D" }, { "family_name": "Fazio", "given_name": "Rosario", "clpid": "Fazio-R" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" } ], "abstract": "We derive experimentally measurable lower bounds for the two-site entanglement of the spin-degrees of freedom of many-body systems with local particle-number fluctuations. Our method aims at enabling the spatially resolved detection of spin-entanglement in Hubbard systems using high-resolution imaging in optical lattices. A possible application is the observation of entanglement generation and spreading during spin impurity dynamics, for which we provide numerical simulations. More generally, the scheme can simplify the entanglement detection in ion chains, Rydberg atoms, or similar atomic systems.", "doi": "10.1088/1367-2630/17/1/013015", "issn": "1367-2630", "publisher": "IOP", "publication": "New Journal of Physics", "publication_date": "2015-01", "series_number": "1", "volume": "17", "issue": "1", "pages": "Art. No. 013015" }, { "id": "authors:0sf5w-ksz63", "collection": "authors", "collection_id": "0sf5w-ksz63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-112738781", "type": "article", "title": "Out-of-equilibrium dynamics and thermalization of string order", "author": [ { "family_name": "Mazza", "given_name": "Leonardo", "clpid": "Mazza-L" }, { "family_name": "Rossini", "given_name": "Davide", "clpid": "Rossini-D" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Fazio", "given_name": "Rosario", "clpid": "Fazio-R" } ], "abstract": "We investigate the equilibration dynamics of string order in one-dimensional quantum systems. After initializing a spin-1 chain in the Haldane phase, the time evolution of nonlocal correlations following a sudden quench is studied by means of matrix-product-state-based algorithms. Thermalization occurs only for scales up to a horizon growing at a well defined speed, due to the finite maximal velocity at which string correlations can propagate, related to a Lieb-Robinson bound. The persistence of string ordering at finite times is nontrivially related to symmetries of the quenched Hamiltonian. A qualitatively similar behavior is found for the string order of the Mott insulating phase in the Bose-Hubbard chain. This paves the way towards an experimental testing of our results in present cold-atom setups.", "doi": "10.1103/PhysRevB.90.020301", "issn": "1098-0121", "publisher": "American Physical Society", "publication": "Physical Review B", "publication_date": "2014-07-01", "series_number": "2", "volume": "90", "issue": "2", "pages": "Art. No. 020301" }, { "id": "authors:vpz51-cvp82", "collection": "authors", "collection_id": "vpz51-cvp82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-073235392", "type": "article", "title": "Microscopic observation of magnon bound states and their dynamics", "author": [ { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Schau\u00df", "given_name": "Peter", "clpid": "Schau\u00df-P" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Hild", "given_name": "Sebastian", "clpid": "Hild-S" }, { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Gross", "given_name": "Christian", "clpid": "Gross-C" } ], "abstract": "The existence of bound states of elementary spin waves (magnons) in one-dimensional quantum magnets was predicted almost 80\u2009years ago. Identifying signatures of magnon bound states has so far remained the subject of intense theoretical research and their detection has proved challenging for experiments. Ultracold atoms offer an ideal setting in which to find such bound states by tracking the spin dynamics with single-spin and single-site resolution, following a local excitation. Here we use in situ correlation measurements to observe two-magnon bound states directly in a one-dimensional Heisenberg spin chain comprising ultracold bosonic atoms in an optical lattice. We observe the quantum dynamics of free and bound magnon states through time-resolved measurements of two spin impurities. The increased effective mass of the compound magnon state results in slower spin dynamics as compared to single-magnon excitations. We also determine the decay time of bound magnons, which is probably limited by scattering on thermal fluctuations in the system. Our results provide a new way of studying fundamental properties of quantum magnets and, more generally, properties of interacting impurities in quantum many-body systems.", "doi": "10.1038/nature12541", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2013-10-03", "series_number": "7469", "volume": "502", "issue": "7469", "pages": "76-79" }, { "id": "authors:phrac-7dg39", "collection": "authors", "collection_id": "phrac-7dg39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160526-145805570", "type": "article", "title": "Single-site- and single-atom-resolved measurement of correlation functions", "author": [ { "family_name": "Endres", "given_name": "M.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Cheneau", "given_name": "M.", "clpid": "Cheneau-M" }, { "family_name": "Fukuhara", "given_name": "T.", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Weitenberg", "given_name": "C.", "clpid": "Weitenberg-C" }, { "family_name": "Schau\u00df", "given_name": "P.", "clpid": "Schau\u00df-P" }, { "family_name": "Gross", "given_name": "C.", "clpid": "Gross-C" }, { "family_name": "Mazza", "given_name": "L.", "clpid": "Mazza-L" }, { "family_name": "Ba\u00f1uls", "given_name": "M. C.", "clpid": "Ba\u00f1uls-M-C" }, { "family_name": "Pollet", "given_name": "L.", "clpid": "Pollet-L" }, { "family_name": "Bloch", "given_name": "I.", "clpid": "Bloch-I" }, { "family_name": "Kuhr", "given_name": "S.", "clpid": "Kuhr-S" } ], "abstract": "Correlation functions play an important role for the theoretical and experimental characterization of many-body systems. In solid-state systems, they are usually determined through scattering experiments, whereas in cold gases systems, time-of-flight, and in situ absorption imaging are the standard observation techniques. However, none of these methods allow the in situ detection of spatially resolved correlation functions at the single-particle level. Here, we give a more detailed account of recent advances in the detection of correlation functions using in situ fluorescence imaging of ultracold bosonic atoms in an optical lattice. This method yields single-site- and single-atom-resolved images of the lattice gas in a single experimental run, thus gaining direct access to fluctuations in the many-body system. As a consequence, the detection of correlation functions between an arbitrary set of lattice sites is possible. This enables not only the detection of two-site correlation functions but also the evaluation of non-local correlations, which originate from an extended region of the system and are used for the characterization of quantum phases that do not possess (quasi-)long-range order in the traditional sense.", "doi": "10.1007/s00340-013-5552-9", "issn": "0946-2171", "publisher": "Springer Verlag", "publication": "Applied Physics B: Lasers and Optics", "publication_date": "2013-10", "series_number": "1", "volume": "113", "issue": "1", "pages": "27-39" }, { "id": "authors:pamtw-t7z95", "collection": "authors", "collection_id": "pamtw-t7z95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160526-144821048", "type": "article", "title": "Non-local order in Mott insulators, duality and Wilson loops", "author": [ { "family_name": "Rath", "given_name": "Steffen Patrick", "clpid": "Rath-S-P" }, { "family_name": "Simeth", "given_name": "Wolfgang", "clpid": "Simeth-W" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Zwerger", "given_name": "Wilhelm", "clpid": "Zwerger-W" } ], "abstract": "It is shown that the Mott insulating and superfluid phases of bosons in an optical lattice may be distinguished by a non-local 'parity order parameter' which is directly accessible via single site resolution imaging. In one dimension, the lattice Bose model is dual to a classical interface roughening problem. We use known exact results from the latter to prove that the parity order parameter exhibits long range order in the Mott insulating phase, consistent with recent experiments by Endres et al. [M. Endres, M. Cheneau, T. Fukuhara, C. Weitenberg, P. Schau\u00df, C. Gross, L. Mazza, M.C. Ba\u00f1uls, L. Pollet, I. Bloch, et al., Science 334 (2011) 200]. In two spatial dimensions, the parity order parameter can be expressed in terms of an equal time Wilson loop of a non-trivial U(1) gauge theory in 2+1 dimensions which exhibits a transition between a Coulomb and a confining phase. The negative logarithm of the parity order parameter obeys a perimeter law in the Mott insulator and is enhanced by a logarithmic factor in the superfluid.", "doi": "10.1016/j.aop.2013.04.006", "issn": "0003-4916", "publisher": "Elsevier", "publication": "Annals of Physics", "publication_date": "2013-07", "volume": "334", "pages": "256-271" }, { "id": "authors:rmw96-62210", "collection": "authors", "collection_id": "rmw96-62210", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-105926301", "type": "article", "title": "Quantum dynamics of a mobile spin impurity", "author": [ { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Kantian", "given_name": "Adrian", "clpid": "Kantian-A" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Schau\u00df", "given_name": "Peter", "clpid": "Schau\u00df-P" }, { "family_name": "Hild", "given_name": "Sebastian", "clpid": "Hild-S" }, { "family_name": "Bellem", "given_name": "David", "clpid": "Bellem-D" }, { "family_name": "Schollw\u00f6ck", "given_name": "Ulrich", "clpid": "Schollw\u00f6ck-U" }, { "family_name": "Giamarchi", "given_name": "Thierry", "clpid": "Giamarchi-T" }, { "family_name": "Gross", "given_name": "Christian", "clpid": "Gross-C" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Kuhr", "given_name": "Stefan", "clpid": "Kuhr-S" } ], "abstract": "One of the elementary processes in quantum magnetism is the propagation of spin excitations. Here we study the quantum dynamics of a deterministically created spin-impurity atom, as it propagates in a one-dimensional lattice system. We probe the spatial probability distribution of the impurity at different times using single-site-resolved imaging of bosonic atoms in an optical lattice. In the Mott-insulating regime, the quantum-coherent propagation of a magnetic excitation in the Heisenberg model can be observed using a post-selection technique. Extending the study to the superfluid regime of the bath, we quantitatively determine how the bath affects the motion of the impurity, showing evidence of polaronic behaviour. The experimental data agree with theoretical predictions, allowing us to determine the effect of temperature on the impurity motion. Our results provide a new approach to studying quantum magnetism, mobile impurities in quantum fluids and polarons in lattice systems.", "doi": "10.1038/nphys2561", "issn": "1745-2473", "publisher": "Nature Publishing Group", "publication": "Nature Physics", "publication_date": "2013-02-24", "series_number": "4", "volume": "9", "issue": "4", "pages": "235-241" }, { "id": "authors:gxzgy-dat09", "collection": "authors", "collection_id": "gxzgy-dat09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-073234918", "type": "article", "title": "Observation of spatially ordered structures in a two-dimensional Rydberg gas", "author": [ { "family_name": "Schau\u00df", "given_name": "Peter", "clpid": "Schau\u00df-P" }, { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-T" }, { "family_name": "Hild", "given_name": "Sebastian", "clpid": "Hild-S" }, { "family_name": "Omran", "given_name": "Ahmed", "orcid": "0000-0002-2253-0278", "clpid": "Omran-A" }, { "family_name": "Pohl", "given_name": "Thomas", "clpid": "Pohl-T" }, { "family_name": "Gross", "given_name": "Christian", "clpid": "Gross-C" }, { "family_name": "Kuhr", "given_name": "Stefan", "clpid": "Kuhr-S" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" } ], "abstract": "The ability to control and tune interactions in ultracold atomic gases has paved the way for the realization of new phases of matter. So far, experiments have achieved a high degree of control over short-range interactions, but the realization of long-range interactions has become a central focus of research because it would open up a new realm of many-body physics. Rydberg atoms are highly suited to this goal because the van der Waals forces between them are many orders of magnitude larger than those between ground-state atoms. Consequently, mere laser excitation of ultracold gases can cause strongly correlated many-body states to emerge directly when atoms are transferred to Rydberg states. A key example is a quantum crystal composed of coherent superpositions of different, spatially ordered configurations of collective excitations. Here we use high-resolution, in situ Rydberg atom imaging to measure directly strong correlations in a laser-excited, two-dimensional atomic Mott insulator. The observations reveal the emergence of spatially ordered excitation patterns with random orientation, but well-defined geometry, in the high-density components of the prepared many-body state. Together with a time-resolved analysis, this supports the description of the system in terms of a correlated quantum state of collective excitations delocalized throughout the gas. Our experiment demonstrates the potential of Rydberg gases to realize exotic phases of matter, thereby laying the basis for quantum simulations of quantum magnets with long-range interactions.", "doi": "10.1038/nature11596", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2012-11-01", "series_number": "7422", "volume": "491", "issue": "7422", "pages": "87-91" }, { "id": "authors:swqpj-j1897", "collection": "authors", "collection_id": "swqpj-j1897", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120813-081146702", "type": "article", "title": "The 'Higgs' amplitude mode at the two-dimensional superfluid/Mott insulator transition", "author": [ { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-T" }, { "family_name": "Pekker", "given_name": "David", "clpid": "Pekker-D" }, { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Schau\u03b2", "given_name": "Peter", "clpid": "Schau\u03b2-P" }, { "family_name": "Gross", "given_name": "Christian", "clpid": "Gross-C" }, { "family_name": "Demler", "given_name": "Eugene", "clpid": "Demler-E-A" }, { "family_name": "Kuhr", "given_name": "Stefan", "clpid": "Kuhr-S" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" } ], "abstract": "Spontaneous symmetry breaking plays a key role in our understanding of nature. In relativistic quantum field theory, a broken continuous symmetry leads to the emergence of two types of fundamental excitation: massless Nambu\u2013Goldstone modes and a massive 'Higgs' amplitude mode. An excitation of Higgs type is of crucial importance in the standard model of elementary particle physics, and also appears as a fundamental collective mode in quantum many-body systems. Whether such a mode exists in low-dimensional systems as a resonance-like feature, or whether it becomes overdamped through coupling to Nambu\u2013Goldstone modes, has been a subject of debate. Here we experimentally find and study a Higgs mode in a two-dimensional neutral superfluid close to a quantum phase transition to a Mott insulating phase. We unambiguously identify the mode by observing the expected reduction in frequency of the onset of spectral response when approaching the transition point. In this regime, our system is described by an effective relativistic field theory with a two-component quantum field which constitutes a minimal model for spontaneous breaking of a continuous symmetry. Additionally, all microscopic parameters of our system are known from first principles and the resolution of our measurement allows us to detect excited states of the many-body system at the level of individual quasiparticles. This allows for an in-depth study of Higgs excitations that also addresses the consequences of the reduced dimensionality and confinement of the system. Our work constitutes a step towards exploring emergent relativistic models with ultracold atomic gases.", "doi": "10.1038/nature11255", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2012-07-26", "series_number": "7408", "volume": "487", "issue": "7408", "pages": "454-458" }, { "id": "authors:12j8w-b1z20", "collection": "authors", "collection_id": "12j8w-b1z20", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160526-151342040", "type": "article", "title": "Light-cone-like spreading of correlations in a quantum many-body system", "author": [ { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Barmettler", "given_name": "Peter", "clpid": "Barmettler-P" }, { "family_name": "Poletti", "given_name": "Dario", "clpid": "Poletti-D" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Schau\u00df", "given_name": "Peter", "clpid": "Schau\u00df-P" }, { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Gross", "given_name": "Christian", "clpid": "Gross-C" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Kollath", "given_name": "Corinna", "clpid": "Kollath-C" }, { "family_name": "Kuhr", "given_name": "Stefan", "clpid": "Kuhr-S" } ], "abstract": "In relativistic quantum field theory, information propagation is bounded by the speed of light. No such limit exists in the non-relativistic case, although in real physical systems, short-range interactions may be expected to restrict the propagation of information to finite velocities. The question of how fast correlations can spread in quantum many-body systems has been long studied. The existence of a maximal velocity, known as the Lieb\u2013Robinson bound, has been shown theoretically to exist in several interacting many-body systems (for example, spins on a lattice)\u2014such systems can be regarded as exhibiting an effective light cone that bounds the propagation speed of correlations. The existence of such a 'speed of light' has profound implications for condensed matter physics and quantum information, but has not been observed experimentally. Here we report the time-resolved detection of propagating correlations in an interacting quantum many-body system. By quenching a one-dimensional quantum gas in an optical lattice, we reveal how quasiparticle pairs transport correlations with a finite velocity across the system, resulting in an effective light cone for the quantum dynamics. Our results open perspectives for understanding the relaxation of closed quantum systems far from equilibrium, and for engineering the efficient quantum channels necessary for fast quantum computations.", "doi": "10.1038/nature10748", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2012-01-26", "series_number": "7382", "volume": "481", "issue": "7382", "pages": "484-487" }, { "id": "authors:449g0-07y02", "collection": "authors", "collection_id": "449g0-07y02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-111401113", "type": "article", "title": "Observation of Correlated Particle-Hole Pairs and String Order in Low-Dimensional Mott Insulators", "author": [ { "family_name": "Endres", "given_name": "M.", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Cheneau", "given_name": "M.", "clpid": "Cheneau-M" }, { "family_name": "Fukuhara", "given_name": "T.", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Weitenberg", "given_name": "C.", "clpid": "Weitenberg-C" }, { "family_name": "Schauss", "given_name": "P.", "clpid": "Schauss-P" }, { "family_name": "Gross", "given_name": "C.", "clpid": "Gross-C" }, { "family_name": "Mazza", "given_name": "L.", "clpid": "Mazza-L" }, { "family_name": "Banuls", "given_name": "M. C.", "clpid": "Banuls-M-C" }, { "family_name": "Pollet", "given_name": "L.", "clpid": "Pollet-L" }, { "family_name": "Bloch", "given_name": "I.", "clpid": "Bloch-I" }, { "family_name": "Kuhr", "given_name": "S.", "clpid": "Kuhr-S" } ], "abstract": "Quantum phases of matter are characterized by the underlying correlations of the many-body system. Although this is typically captured by a local order parameter, it has been shown that a broad class of many-body systems possesses a hidden nonlocal order. In the case of bosonic Mott insulators, the ground state properties are governed by quantum fluctuations in the form of correlated particle-hole pairs that lead to the emergence of a nonlocal string order in one dimension. By using high-resolution imaging of low-dimensional quantum gases in an optical lattice, we directly detect these pairs with single-site and single-particle sensitivity and observe string order in the one-dimensional case.", "doi": "10.1126/science.1209284", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2011-10-14", "series_number": "6053", "volume": "334", "issue": "6053", "pages": "200-203" }, { "id": "authors:5vvpv-5dw67", "collection": "authors", "collection_id": "5vvpv-5dw67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-104431656", "type": "article", "title": "Coherent Light Scattering from a Two-Dimensional Mott Insulator", "author": [ { "family_name": "Weitenberg", "given_name": "Christof", "clpid": "Weitenberg-C" }, { "family_name": "Schau\u00df", "given_name": "Peter", "clpid": "Schau\u00df-P" }, { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Kuhr", "given_name": "Stefan", "clpid": "Kuhr-S" } ], "abstract": "We experimentally demonstrate coherent light scattering from an atomic Mott insulator in a two-dimensional lattice. The far-field diffraction pattern of small clouds of a few hundred atoms was imaged while simultaneously laser cooling the atoms with the probe beams. We describe the position of the diffraction peaks and the scaling of the peak parameters by a simple analytic model. In contrast to Bragg scattering, scattering from a single plane yields diffraction peaks for any incidence angle. We demonstrate the feasibility of detecting spin correlations via light scattering by artificially creating a one-dimensional antiferromagnetic order as a density wave and observing the appearance of additional diffraction peaks.", "doi": "10.1103/PhysRevLett.106.215301", "issn": "0031-9007", "publisher": "American Physical Society", "publication": "Physical Review Letters", "publication_date": "2011-05-27", "series_number": "21", "volume": "106", "issue": "21", "pages": "Art. No. 215301" }, { "id": "authors:g0ktj-wqa96", "collection": "authors", "collection_id": "g0ktj-wqa96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160527-064521287", "type": "article", "title": "Single-spin addressing in an atomic Mott insulator", "author": [ { "family_name": "Weitenberg", "given_name": "Christof", "clpid": "Weitenberg-C" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Sherson", "given_name": "Jacob F.", "clpid": "Sherson-J-F" }, { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Schau\u00df", "given_name": "Peter", "clpid": "Schau\u00df-P" }, { "family_name": "Fukuhara", "given_name": "Takeshi", "clpid": "Fukuhara-Takeshi" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Kuhr", "given_name": "Stefan", "clpid": "Kuhr-S" } ], "abstract": "Ultracold atoms in optical lattices provide a versatile tool with which to investigate fundamental properties of quantum many-body systems. In particular, the high degree of control of experimental parameters has allowed the study of many interesting phenomena, such as quantum phase transitions and quantum spin dynamics. Here we demonstrate how such control can be implemented at the most fundamental level of a single spin at a specific site of an optical lattice. Using a tightly focused laser beam together with a microwave field, we were able to flip the spin of individual atoms in a Mott insulator with sub-diffraction-limited resolution, well below the lattice spacing. The Mott insulator provided us with a large two-dimensional array of perfectly arranged atoms, in which we created arbitrary spin patterns by sequentially addressing selected lattice sites after freezing out the atom distribution. We directly monitored the tunnelling quantum dynamics of single atoms in the lattice prepared along a single line, and observed that our addressing scheme leaves the atoms in the motional ground state. The results should enable studies of entropy transport and the quantum dynamics of spin impurities, the implementation of novel cooling schemes, and the engineering of quantum many-body phases and various quantum information processing applications.", "doi": "10.1038/nature09827", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2011-03-17", "series_number": "7338", "volume": "471", "issue": "7338", "pages": "319-324" }, { "id": "authors:ztmng-pwv95", "collection": "authors", "collection_id": "ztmng-pwv95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160526-125751057", "type": "article", "title": "Single-atom-resolved fluorescence imaging of an atomic Mott insulator", "author": [ { "family_name": "Sherson", "given_name": "Jacob F.", "clpid": "Sherson-J-F" }, { "family_name": "Weitenberg", "given_name": "Christof", "clpid": "Weitenberg-C" }, { "family_name": "Endres", "given_name": "Manuel", "orcid": "0000-0002-4461-224X", "clpid": "Endres-M" }, { "family_name": "Cheneau", "given_name": "Marc", "clpid": "Cheneau-M" }, { "family_name": "Bloch", "given_name": "Immanuel", "clpid": "Bloch-I" }, { "family_name": "Kuhr", "given_name": "Stefan", "clpid": "Kuhr-S" } ], "abstract": "The reliable detection of single quantum particles has revolutionized the field of quantum optics and quantum information processing. For several years, researchers have aspired to extend such detection possibilities to larger-scale, strongly correlated quantum systems, in order to record in situ images of a quantum fluid in which each underlying quantum particle is detected. Here we report fluorescence imaging of strongly interacting bosonic Mott insulators in an optical lattice with single-atom and single-site resolution. From our images, we fully reconstruct the atom distribution on the lattice and identify individual excitations with high fidelity. A comparison of the radial density and variance distributions with theory provides a precise in situ temperature and entropy measurement from single images. We observe Mott-insulating plateaus with near-zero entropy and clearly resolve the high-entropy rings separating them, even though their width is of the order of just a single lattice site. Furthermore, we show how a Mott insulator melts with increasing temperature, owing to a proliferation of local defects. The ability to resolve individual lattice sites directly opens up new avenues for the manipulation, analysis and applications of strongly interacting quantum gases on a lattice. For example, one could introduce local perturbations or access regions of high entropy, a crucial requirement for the implementation of novel cooling schemes.", "doi": "10.1038/nature09378", "issn": "0028-0836", "publisher": "Nature Publishing Group", "publication": "Nature", "publication_date": "2010-09-02", "series_number": "7311", "volume": "467", "issue": "7311", "pages": "68-72" } ]