Nanoelectromechanical systems (NEMS) resonators operating in the quantum regime provide a powerful platform for investigating mechanical motion at its most fundamental level. Their intrinsic ability to couple to environmental degrees of freedom, along with the long coherence times of their mechanical excitations (phonons), makes them particularly promising for quantum information and sensing applications. However, in this regime, the performance of NEMS resonators are predominantly affected by intrinsic material defects, acting as two-level systems (TLS). These quantum defects, ubiquitous in solid-state quantum devices at low temperatures, can exchange energy with their host field, causing dissipation and noise. Despite these dominant effects, the microscopic origin of such quantum defects is still unknown, and their interactions with phononic devices have been elusive.
\r\n\r\nHere, we present a detailed investigation into these interactions between quantum defects and phonons within piezoelectric lithium niobate NEMS resonator shielded by phononic crystals. We identify TLS defects as the primary source of excess noise at millikelvin temperatures, limiting their performance and sensitivity. By controlling the TLS frequency in situ with the application of electric field---and strain field due to piezoelectricity---we demonstrate strong resonant coupling between a mechanical mode of our NEMS resonator and a single, intrinsic TLS. Varying the resonant drive and/or temperature allows controlled ascent of the nonequidistant energy ladder and reveals the dressed states of the hybridized system. Fluctuations of the TLS on and off resonance with the mode induces switching between dressed and bare states; this elucidates the complex quantum nature of TLS-like defects in mesoscopic systems. We demonstrate that individual TLS defects can be precisely controlled and manipulated, transforming them from detrimental dissipation and noise sources into valuable quantum resources. The ability to harness this intrinsic nonlinearity of a nanomechanical resonator with quantum defects offers new directions towards quantum sensing and information.
", "doi": "10.7907/3ypf-a284", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17837", "collection": "thesis", "collection_id": "17837", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01262026-214753026", "type": "thesis", "title": "Interfacing Long-Lived Mechanical Oscillators and Superconducting Quantum Circuits", "author": [ { "family_name": "Bozkurt", "given_name": "Alk\u0131m Berke", "orcid": "0000-0003-0633-8902", "clpid": "Bozkurt-Alk\u0131m-Berke" } ], "thesis_advisor": [ { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" } ], "thesis_committee": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Mechanical oscillators in the quantum regime hold promise for quantum sensing, frequency conversion and information processing. Because mechanical motion is linear, coupling to an external nonlinear system, such as a qubit, is essential for these applications. Recent advances in piezoelectric interfaces between mechanical oscillators and superconducting qubits have successfully demonstrated precise control of non-classical states of motion. However, challenges associated with heterogeneous integration of piezoelectric materials have limited mechanical quality factors in these systems to around one million, constraining their broader utility.
\r\n\r\nIn this thesis, we explore an alternative approach that harnesses the nonlinearity of electrostatic forces to engineer interactions between superconducting circuits and mechanical oscillators. This strategy allows us to employ mechanical oscillators made of silicon, a non-piezoelectric material with extremely low acoustic loss. We reach the strong coupling regime between a superconducting qubit and a long-lived mechanical oscillator with a quality-factor of around a billion. We employ this system to generate non-classical states of motion that exhibit clear signatures of quantum behavior. Furthermore, we explore the origins of acoustic decoherence and implement strategies to mitigate its impact.
\r\n\r\nThe mechanical lifetimes, which exceed those of best superconducting qubits, open new possibilities for storing and processing microwave quantum information in motional states. Furthermore, our material-agnostic approach is broadly applicable to a variety of material platforms that possess significance for quantum science but lack a piezoelectric response.
", "doi": "10.7907/wz3n-fn09", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17856", "collection": "thesis", "collection_id": "17856", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02042026-041427925", "type": "thesis", "title": "Techniques Toward the Wafer-Scale Fabrication of Enzyme-Based Sensors", "author": [ { "family_name": "Smith", "given_name": "Richard Daniel", "orcid": "0000-0001-9384-105X", "clpid": "Smith-Richard-Daniel" } ], "thesis_advisor": [ { "family_name": "Scherer", "given_name": "Axel", "orcid": "0000-0002-2160-9064", "clpid": "Scherer-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" }, { "family_name": "Scherer", "given_name": "Axel", "orcid": "0000-0002-2160-9064", "clpid": "Scherer-A" }, { "family_name": "Gao", "given_name": "Wei", "orcid": "0000-0002-8503-4562", "clpid": "Gao-Wei" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Roukes", "given_name": "Michael Lee", "orcid": "0000-0002-2916-6026", "clpid": "Roukes-M-L" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Wafer-scale fabrication of transducers directly on CMOS dies can minimize device size, increase the throughput and improve uniformity. Doing so with materials sensitive to the conditions encountered during typical microfabrication processes, such as enzymes, remains a challenge.
\r\n\r\nThis thesis investigates aspects of the performance and fabrication processes of electrochemical enzyme-based glucose-sensing transducers, intended for monolithic, implantable wireless sensors. The described work builds on past efforts in the Scherer group and focuses on the transducer fabrication compatible with CMOS wafers.
\r\n\r\nIn the first part, the pre-existing, enzyme-film lift-off patterning process is analyzed. The electrochemical processes of the three glucose oxidase-platinum electrodes are first investigated for the use in sensor diagnostics. The topography of the film is then related to the geometry of the patterns and to the performance of these transducers. Modifications are then made to reduce variation and improve yield. A process to optically profile such structures was also developed to better interpret the non-uniformity from thin film interference.
\r\n\r\nThe second part of this thesis describes the development and processing for plasma etch patterning the enzyme films. This aims to separate the uniformity of the film deposition from the definition of the boundaries, as occurs in many microfabrication processes with less sensitive materials. Strategies were developed that limit the optical, thermal, and chemical degradation of the enzyme activity. The resulting process demonstrated the feasibility of dry etch patterning functional enzyme films without loss of activity. Further, it clarified that improved structural uniformity can yield improved performance uniformity.
\r\n\r\nA final, tangential section investigates a positive tone electron beam lithography process that can be entirely performed in vacuum. Myo-inositol, an electron beam sensitive material, was unexpectedly found and refined. Dry processed negative tone resists avoid pattern collapse during wet development, but analogous positive-tone processes remain elusive. Myo-inositol films, deposited with thermal evaporation, were exposed with electron beams and then developed by subsequent heating. With dry etching and plasma stripping, the full dry process could be implemented in a vacuum cluster tool. While early in development and with challenges remaining, sub 100 nm features were transferred into an underlying thin metal film with this process.
", "doi": "10.7907/b6e8-ws51", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18761", "collection": "thesis", "collection_id": "18761", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06012026-223645069", "primary_object_url": { "basename": "Thesis.pdf", "content": "final", "filesize": 13675713, "license": "other", "mime_type": "application/pdf", "url": "/18761/1/Thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Measuring and Characterizing Ultrafast Quantum States Using Nanophotonic Optical Parametric Amplifiers", "author": [ { "family_name": "Sendonaris", "given_name": "Elina Maria", "orcid": "0009-0003-4209-2783", "clpid": "Sendonaris-Elina-Maria" } ], "thesis_advisor": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Photonics offers the potential for large-scale, room-temperature, and ultrafast quantum operations. Multiplexing pulses of light allows for high throughput speeds and dense encoding, with tens of thousands of optical modes being present in a time as short as a microsecond. However, the measurement speed of electronic devices such as photodetectors is currently one bottleneck in such time-multiplexed scalability, because many quantum optical protocols rely on measurement, including state preparation, feed-forward, and feedback. Furthermore, characterization of quantum states and modes is essential for their effective use. Using nanophotonic optical parametric amplifiers (OPAs) presents one way to circumvent the measurement limitations of current quantum photonic schemes. Their large amplification bandwidth, enabled by dispersion engineering on nanophotonic integrated platforms, allows information encoded in femtosecond-scale, THz-bandwidth, multimode quantum optical states to be accessed with nonlinear optical interactions.
\r\n \r\nIn this work, we show how ultra-broadband integrated nanophotonic OPAs can be used to measure ultrafast and multimode quantum states of light. First, we explore the single-photon detection capabilities of OPAs, showing that current OPAs operating in the Gaussian regime are capable of 250 MHz photon count rates with 26% efficiency and a 2% dark count probability. We also show how non-Gaussian operation through pump depletion, with performance that approaches state-of-the-art photon detectors in terms of efficiency and dark count rate while retaining ultrafast operation, can become experimentally possible with a higher nonlinear coupling rate and lower loss. Next, we use nanophotonic OPAs to both generate and characterize multimode ultrafast squeezed vacuum. We use the photocurrent distribution of amplified squeezed vacuum to recover 2.41 dB of squeezing in one mode of a 154-fs multimode squeezed pulse and reconstruct its Wigner distribution. Finally, we investigate the capabilities of broadband nanophotonic OPAs to determine the temporal mode structure and quadrature variances of ultra-broadband temporally multimode quantum states by adapting frequency-resolved optical gating to the quantum regime. We numerically show the successful full characterization of a multimode squeezed state, even in the presence of noise. Together, these results establish OPAs as a valuable measurement device for measuring ultrafast quantum pulses and learning the structure of multimode quantum states, and they provide one building block towards a framework for scalable continuous-variable quantum photonics in which state generation, manipulation, and characterization occur within the same nanophotonic platform.
", "doi": "10.7907/ggz4-5161", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18685", "collection": "thesis", "collection_id": "18685", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05292026-040935004", "type": "thesis", "title": "Collective Interactions in Cavity-Coupled Rare-Earth Ion Ensembles for Quantum Technologies", "author": [ { "family_name": "Fukumori", "given_name": "Rikuto", "orcid": "0000-0003-0896-4261", "clpid": "Fukumori-Rikuto" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-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" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Rare-earth ions in solids are a promising platform for quantum technologies because they combine atom-like optical and spin transitions with the practical advantages of a solid-state host compatible with optical and microwave resonators. This thesis studies cavity-coupled 171Yb3+ ensembles in oxide crystals as a platform for collective cavity-QED and many-body physics, motivated by the goal of using rare-earth ions as hybrid quantum interconnects for quantum computation and networking. The central theme is that coupling many rare-earth ions to a shared resonator mode creates a rich setting for studying fundamental collective and many-body physics, while also providing a practical route to microwave-to-optical conversion, protected spin storage, and interfaces between superconducting circuits and optical photons.
\r\n\r\nIn 171Yb3+:YVO4, a nanophotonic cavity coupled to an inhomogeneously broadened ion ensemble reveals collective cavity QED in a solid. This work led to the discovery of collectively induced transparency, a cavity-QED phenomenon arising from collective interference in a driven, disordered ensemble. The same system exhibits optical superradiance and subradiance, and supports an interacting microwave spin system in which dipolar exchange competes with disorder, allowing studies of quantum thermalization. With Floquet control, these spin dynamics can be modified to reveal discrete time-crystal signatures. In 171Yb3+:CaWO4, related experiments demonstrate microwave superradiance, one-axis twisting, and many-body gap protection in a solid-state spin ensemble.
\r\n\r\nThese physics results are developed alongside quantum-technology applications. The 171Yb3+:YVO4 platform further enables low-noise microwave-to-optical transduction with percent-level on-chip efficiency and added noise near the single-photon level, establishing rare-earth ensembles as a promising approach to optical interconnects for superconducting quantum systems. In 171Yb3+:CaWO4, cavity-mediated gap protection extends Ramsey coherence and supports the development of a spin-based microwave quantum memory, including a classical-regime demonstration of storage and optical readout. The final part develops the superconducting qubit architecture needed to drive a rare-earth transducer with single microwave excitations, including qubit readout, tunable-coupler SWAP control, and cable-mode characterization. Together, these results establish cavity-coupled rare-earth ensembles as a versatile platform for studying fundamental cavity QED and many-body physics and for developing quantum technologies.
", "doi": "10.7907/4zys-mm04", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18459", "collection": "thesis", "collection_id": "18459", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03302026-202907452", "primary_object_url": { "basename": "AAHPhDThesis_03272026.pdf", "content": "final", "filesize": 58304932, "license": "other", "mime_type": "application/pdf", "url": "/18459/1/AAHPhDThesis_03272026.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Atomic Layer Processing of Thin Film Superconductors for Superconducting Electronics", "author": [ { "family_name": "Hossain", "given_name": "Azmain Abrawr", "orcid": "0000-0002-8441-0183", "clpid": "Hossain-Azmain-Abrawr" } ], "thesis_advisor": [ { "family_name": "Minnich", "given_name": "Austin J.", "orcid": "0000-0002-9671-9540", "clpid": "Minnich-A-J" } ], "thesis_committee": [ { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Falson", "given_name": "Joseph", "orcid": "0000-0003-3183-9864", "clpid": "Falson-Joseph" }, { "family_name": "Kooi", "given_name": "Jacob W.", "orcid": "0000-0002-6610-0384", "clpid": "Kooi-J-W" }, { "family_name": "Minnich", "given_name": "Austin J.", "orcid": "0000-0002-9671-9540", "clpid": "Minnich-A-J" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "State-of-the-art superconducting devices such as qubits, microwave kinetic inductance detectors (MKIDs), and superconducting-insulator-superconducting (SIS) mixers are fabricated using dry etching, typically reactive ion etching (RIE). The microwave performance of MKIDs and qubits is currently limited by interface and surface loss thought to arise from nanofabrication-induced damage and atmospheric exposure. For SIS mixers, it is important to fabricate layers with sub-nanometer etching precision and low surface roughness (< 0.5 nm). However, RIE is generally unable to meet these criteria due to the continuous nature of the etching process and the use of high energy ions. Additionally, RIE has been shown to lead to almost 10 nm of sub-surface damage, which can limit the performance of superconducting devices where the interfaces are critical to performance. In all of these devices, improving etch-depth control and achieving low surface roughness through a low-damage etching process is essential to improving state-of-the-art devices and enabling new device architectures.
\r\n\r\nIn this thesis, we investigate atomic layer processing techniques for thin-film metal nitride superconductors, namely atomic layer deposition (ALD) and atomic layer etching (ALE) being of special focus. ALD and ALE are nanofabrication methods capable of Angstrom-scale control and result in substantially less damage than standard methods such as RIE. Beyond ALD and ALE, we also develop and investigate a new plasma chemistry to etch magnesium diboride, which previously did not have a known chemical dry etch. We then use these techniques to fabricate superconductor-insulator-superconductor junctions and analyze their current-voltage characteristics.
", "doi": "10.7907/pz9e-py53", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18476", "collection": "thesis", "collection_id": "18476", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04072026-143808452", "type": "thesis", "title": "Scalable Arrays From Millimeter-Wave Sensing to Microwave Wireless Power Transfer", "author": [ { "family_name": "Ayling", "given_name": "Alex Eben", "orcid": "0009-0008-5440-7785", "clpid": "Ayling-Alex-Eben" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Siegel", "given_name": "Peter H.", "orcid": "0000-0002-2539-4646", "clpid": "Siegel-P-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Wireless power transfer at a distance, long relegated to the realm of science fiction, has seen a resurgence in recent years. Chief among its promises is Space-Based Solar Power (SBSP), an ambitious project to deploy kilometer scale photovoltaic arrays in space and beam its power down to Earth using a complementary microwave phased array. The building blocks of the array are phased array tiles, which can be instantiated to produce larger apertures.
\r\n\r\nThe tile must be simultaneously lightweight and flexible for deployment in space, low-cost, high-performance, and scalable. First, the results of the MAPLE mission, which tested wireless power transfer in space using custom flexible arrays, are presented. Using the results of that mission, the design and testing of next-generation, fully flexible 8x8 element phased array tile are presented. The tile is driven by a custom 22-nm CMOS FDSOI RFIC that achieves record efficiency and performance. These results represent not only a step forward toward practical microwave wireless power transfer but offer new directions in communications and sensing driven by flexible arrays.
\r\n\r\nAdditionally, topics on maximum power point tracking in SBSP systems, transmitarrays for SBSP, and the design of a fully-integrated, scalable, and low-cost D-band (110-170GHz) radiator tile are discussed.
", "doi": "10.7907/w440-k235", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18490", "collection": "thesis", "collection_id": "18490", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04152026-101519191", "primary_object_url": { "basename": "Gihwan_Kim_PhD_Thesis_042026.pdf", "content": "final", "filesize": 31427058, "license": "other", "mime_type": "application/pdf", "url": "/18490/1/Gihwan_Kim_PhD_Thesis_042026.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Tailoring Tunable Interactions in Superconducting Circuits Using Many to No Modes", "author": [ { "family_name": "Kim", "given_name": "Gihwan", "orcid": "0009-0009-3695-8118", "clpid": "Kim-Gihwan" } ], "thesis_advisor": [ { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" } ], "thesis_committee": [ { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Brandao", "given_name": "Fernando", "orcid": "0000-0003-3866-9378", "clpid": "Brand\u00e3o-F-G-S-L" }, { "family_name": "Refael", "given_name": "Gil", "orcid": "0009-0007-4566-8441", "clpid": "Refael-G" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Tunable couplings are a central requirement for scalable quantum processing with superconducting quantum circuits. Practical quantum processors must dynamically reconfigure their interaction landscape to accommodate different quantum operations, including idle, single-qubit gates, two-qubit gates, readout, and reset, while maintaining high coherence and suppressing spurious couplings. While widely used tunable interaction approaches rely on single-mode mediation, they are often constrained by nearest-neighbor connectivity, limited on-off ratios, and stringent requirements on qubit frequency allocation.
\r\n\r\nThis thesis develops and studies novel strategies for tailoring tunable interactions by moving beyond single-mode mediation, spanning multimode engineered interactions and modeless interaction schemes (\"many to no modes\"), while accounting for realistic constraints in superconducting hardware. Using a microwave metamaterial waveguide realized by coupled resonator arrays, I demonstrate tunable dissipative interactions that allow on-demand, fast, and high switching-ratio photon emission from a transmon used as a multi-level quantum emitter. This capability is leveraged to achieve deterministic generation of multidimensional photonic cluster states, as well as unconditional reset and leakage reduction of frequency-tunable superconducting qubits.
\r\n\r\nComplementary to these multimode dissipative tunable interactions, this thesis also introduces architectures that realize tunable interactions mediated by many coherent modes or by no mediating modes. I discuss a long-range interaction scheme between superconducting dual-rail qubits mediated by spatially extended eigenmodes of a coupled-resonator array bus. Finally, I propose and analyze a novel modeless coupling architecture based on a SQUID coupler which provides intrinsic cross-Kerr interactions, enabling fast, hybridization-free CZ gates for far-detuned pairs, and discuss its implications for miniaturization of superconducting quantum processors.
", "doi": "10.7907/2td2-4z28", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17498", "collection": "thesis", "collection_id": "17498", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06272025-211326959", "type": "thesis", "title": "A High-Efficiency, Low-Noise Platform for Microwave-to-Optical Quantum Transduction", "author": [ { "family_name": "Sonar", "given_name": "Sameer Anil", "orcid": "0000-0002-1082-9360", "clpid": "Sonar-Sameer-Anil" } ], "thesis_advisor": [ { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Quantum computing platforms based on superconducting qubits have achieved remarkable progress in recent years, with significant advancements in quantum error correction, coherence times, and gate fidelities. However, the path to large-scale, fault-tolerant quantum computing faces a critical scaling bottleneck: the physical limits of single-chip architectures. Integrating millions of qubits on a single superconducting chip presents formidable engineering challenges, including increased thermal load, crosstalk, and complex wiring within the dilution refrigerator.
\r\n\r\nA promising approach to overcome these limitations is to interconnect multiple smaller superconducting quantum processors via a quantum network, allowing for distributed quantum computation. In this context, telecom-wavelength optical photons (around 1550 nm or 200 THz) are particularly attractive for transmitting quantum information across long distances due to their low propagation loss in optical fiber and negligible thermal occupation at room temperature. However, superconducting qubits typically operate at microwave frequencies (around 5-10 GHz), leading to a fundamental mismatch in operating frequencies that prevents direct coupling between these two domains.
\r\n\r\nThis five-orders-of-magnitude frequency mismatch poses a major challenge for coherent quantum transduction, requiring a highly efficient, low-noise interface to faithfully convert quantum states between microwave and optical photons. A leading approach for transduction involves piezo-optomechanical platforms, where an intermediary acoustic resonator facilitates the conversion between microwave photons and microwave acoustic phonons, which are then converted to optical photons. However, existing designs often suffer from poor conversion efficiency and added noise due to geometric constraints and substrate heating, limiting their scalability for real-world quantum networks. In the first part of this thesis, I will introduce an optimized two-dimensional optomechanical crystal platform with a side-coupled optical waveguide. This geometry significantly improves the noise-efficiency metric for optical photon-acoustic phonon conversion. I will then discuss the integration of piezo-acoustic circuits into these two-dimensional crystals to realize a full microwave-to-optical transducer. I will cover the underlying design principles, fabrication processes, and preliminary measurement results, highlighting the potential of this platform for enabling future quantum communication and distributed quantum computing.
\r\n\r\nAnother critical challenge in quantum networking is the frequency mismatch that arises when attempting to interfere photons emitted by different quantum nodes. This mismatch is primarily caused by variations in fabrication processes. In the second part of this thesis, I will present a novel post-fabrication tuning technique for piezo-optomechanical transducers, based on atomic force microscope (AFM) nano-oxidation. By applying a voltage bias to the AFM tip, we can selectively oxidize the surface of the dielectric device, introducing a controlled, localized change in refractive index and mechanical properties. This allows for precise tuning of both optical and acoustic resonance frequencies. I will demonstrate the effectiveness of this technique through experimental results at both room and cryogenic temperatures, highlighting its potential for scaling quantum networks.
", "doi": "10.7907/1cbe-vs09", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17141", "collection": "thesis", "collection_id": "17141", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04072025-222314586", "primary_object_url": { "basename": "Caltech_Thesis_James_Williams-20250610.pdf", "content": "final", "filesize": 7801901, "license": "other", "mime_type": "application/pdf", "url": "/17141/4/Caltech_Thesis_James_Williams-20250610.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Ultrafast Quantum State Generation and Measurement in Nonlinear Nanophotonics", "author": [ { "family_name": "Williams", "given_name": "James Anthony", "orcid": "0000-0001-9073-5745", "clpid": "Williams-James-Anthony" } ], "thesis_advisor": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Scherer", "given_name": "Axel", "orcid": "0000-0002-2160-9064", "clpid": "Scherer-A" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "While many physical systems, including superconductors, trapped atoms, molecules, and acoustic resonators can process quantum information, photonics holds several fundamental advantages. Most photonics systems not only offer the convenience of room temperature operation but also shed the scalability limitations imposed by cryogenic and high vacuum environments. Integrated photonics has shrunk room-sized experiments to a chip-scale device while improving performance and versatility. Operating at optical frequencies offers information bandwidths orders of magnitude larger than what is achievable with microwave or trapped atom experiments.
\r\n\r\nIn this thesis, we propose nanophotonic optical parametric amplifiers (OPAs) on a thin-film lithium niobate (TFLN) chip-scale platform for quantum information processing. Through dispersion-engineering, we achieve the distortion-free propagation of ultrafast pulses necessary for information clock rates above 1 THz. We investigate OPAs as ultrashort entangled pair sources and generate biphotons with a 165-fs temporal duration. We show that their generation efficiency and signal-to-noise performance is state-of-the-art at 2 \u00b5m and on-par with contemporary telecom-band sources. We explore OPAs as quantum measurement devices, and demonstrate all-optical single-photon level detection with a dead time of 75 fs. Finally, we show that OPAs can be used to recover continuous-variable quantum information by reconstructing the Wigner function of a 2.41 dB squeezed state encoded in a 154-fs pulse. This technique is loss-tolerant and offers a maximum clock speed of 6.5 THz. TFLN hosts a variety of high-performance optical devices including filters, modulators, resonators, III-V gain media, all of which are compatible with OPAs. Our results highlight ultrafast OPAs as the fundamental building blocks needed to realize large-scale circuits for all-optical quantum information processing.
", "doi": "10.7907/s4n5-2405", "publication_date": "2025", "thesis_type": "phd", "thesis_year": "2025" }, { "id": "thesis:16167", "collection": "thesis", "collection_id": "16167", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08282023-193415593", "type": "thesis", "title": "Adaptive Optoelectronic Systems: From Bio- Sensing to Free-Space Optical Communication", "author": [ { "family_name": "Aghlmand", "given_name": "Fatemeh", "orcid": "0000-0002-5103-9314", "clpid": "Aghlmand-Fatemeh" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Murray", "given_name": "Richard M.", "orcid": "0000-0002-5785-7481", "clpid": "Murray-R-M" }, { "family_name": "Scherer", "given_name": "Axel", "orcid": "0000-0002-2160-9064", "clpid": "Scherer-A" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" } ], "local_group": [ { "literal": "MICS Lab (Mixed Mode Integrated Circuits and Systems)" }, { "literal": "div_eng" } ], "abstract": "Portable and point-of-care medical devices are becoming an essential part of today\u2019s medical technology. An affordable personal device that can diagnose and monitor a medical condition in real-time will improve the patient\u2019s life quality in many ways. Additionally, by autonomously providing the suitable treatment, a universal healthcare device can be accessible to most of the population at a low cost. Despite considerable efforts and great outcomes, most of the prior arts in realizing these devices have limitations that hinder their widespread use in portable applications. On the other hand, comprehensive environmental sensing has drawn great attention in the last few years. Monitoring the quality of water, soil, air, and waste is of utmost importance to study their effect on human life and also to recognize the consequence of human actions on the planet.
\r\n\r\nThe most important factors in developing a compact and portable device for medical and environmental applications are their integration level, ease of use with biomarkers, and reliability of the results. Detecting a specific chemical in the biology world relies on a biochemical reaction with a transducer that can convert the resulting signal into a measurable signal in various modalities, such as electrical, magnetic, or optical. Hence, the biosensing device is often a multidisciplinary apparatus that is not readily integrable due to the need for miniaturizing otherwise bulky optical or magnetic components. The key requirement in device miniaturization, though, is to use standard technologies to avoid extra cost and processing time for the device\u2019s mass production. The path towards achieving such a device needs revisiting the existing solutions and the capabilities of the powerful yet affordable CMOS technologies to seamlessly integrate various device components, namely electronics, biology, and optics/magnetics. This dissertation provides an overview of integrated biosensors and presents novel designs in optics and electronics to implement a fully integrated and miniaturized device for medical and environmental applications.
\r\n\r\nFluorescence sensing is one of the most reliable and widespread detection methods with well- established tools in synthetic biology. Specifically, bacterial-based fluorescence sensors offer unsurpassed advantages to labeled detection since bacterial cells, when engineered, can respond to various elements in their surroundings at a low cost and quite efficiently. The use of live bacterial cells is also of great importance in establishing the bidirectional link with the CMOS device. By monitoring the dynamics of the cells\u2019 growth and their protein expression, a desired biology response can be initiated upon receiving the stimulating signal from the device. The conventional methods in fluorescence sensing involve an elaborate setup with many external optical components unsuitable for portable and in vivo applications. Hence, integrating silicon chips and live bacterial biosensors in a miniaturized \"Silicon-Cell\" system can enable a wide range of applications for both sensing and remediation. Such integrated systems need on-chip optical filtering in the wavelength range compatible with fluorescent proteins, which are widely used signal reporters for bacterial biosensors.
\r\n\r\nIn the first part of this dissertation, we introduce a fully integrated fluorescence sensor in 65nm standard CMOS process comprising on-chip bandpass optical filters, photodiodes, and processing circuitry. The metal/dielectric layers in CMOS are employed to implement low- loss cavity-type optical filters, achieving a bandpass response at 600/700nm range suitable to work with fluorescent proteins. The sensitivity of the sensor is further improved in the electrical domain by using a C-TIA with variable switched capacitor gain, a voltage- controlled current source (VCCS), and feedback-controlled low-leakage switches, resulting in a minimum measured current of 1.05fA with SNR >18dB. The sensor can measure the statics/dynamics of the fluorescence signal as well as the growth of living E. coli bacterial cells. Using a differential design and layout, the sensor can distinguish two biochemical signals by measuring two fluorescent proteins encoded in a single bacterial strain. Furthermore, a proof of concept is demonstrated to establish bidirectional communication between living cells and the CMOS chip, using a fluorescent protein regulated by an optogenetic control.
\r\n\r\nIn the second part of this dissertation, we describe a fully integrated high-bandwidth optical receiver for RF-over-free-space optics (RoFSO). This work is motivated by the availability of a wide, unregulated bandwidth at the optical frequencies and the lower cost and setup time due to using atmosphere instead of fiber optics as the communication channel. Nonetheless, the atmospheric link poses serious challenges, including severe beam intensity and phase distortions. Here we present novel solutions at the system and circuit level to make the receiver adaptive and resilient to the mentioned distortions. The chip is designed and implemented in a 28nm CMOS process, and it is shown to achieve a measured gain of 58dB and bandwidth of 18GHz. The link performance is assessed by exposing the system to more than 26dB of optical loss, equivalent to 3.5km of free space distance under moderate visibility conditions. For a proof-of-concept demonstration, an 8Gbps non-coherent DPSK signal with an RF bandwidth of 10GHz is transmitted, resulting in a BER of 1 \u00d7 10\u207b\u2074 for a minimum received power of -30dBm and while consuming 19.2mW power at the receiver.
", "doi": "10.7907/hj19-7516", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:16469", "collection": "thesis", "collection_id": "16469", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06022024-152003367", "primary_object_url": { "basename": "Markowitz_Aaron_2023.pdf", "content": "final", "filesize": 119740237, "license": "cc_by_sa", "mime_type": "application/pdf", "url": "/16469/1/Markowitz_Aaron_2023.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Interferometric Precision Measurement with Macroscopic Silicon Optomechanics", "author": [ { "family_name": "Markowitz", "given_name": "Aaron Gregory", "orcid": "0000-0003-0223-2342", "clpid": "Markowitz-Aaron-Gregory" } ], "thesis_advisor": [ { "family_name": "Adhikari", "given_name": "Rana", "orcid": "0000-0002-5731-5076", "clpid": "Adhikari-R" } ], "thesis_committee": [ { "family_name": "Chen", "given_name": "Yanbei", "orcid": "0000-0002-9730-9463", "clpid": "Chen-Yanbei" }, { "family_name": "McCuller", "given_name": "Lee P.", "orcid": "0000-0003-0851-0593", "clpid": "McCuller-Lee" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Adhikari", "given_name": "Rana", "orcid": "0000-0002-5731-5076", "clpid": "Adhikari-R" } ], "local_group": [ { "literal": "LIGO" }, { "literal": "div_pma" } ], "abstract": "Optomechanical sensors provide our most sensitive measurements of spacetime, including observations of gravitational waves by laser interferometric detectors. However, even state of the art detectors like the Advanced Laser Interferometric Gravitational-Wave Observatory (LIGO) are still tens of orders of magnitude away from the measurement limits imposed by Heisenberg uncertainty. This thesis maps out the contours of mechanical and optical losses limiting next generation gravitational wave interferometers, and describes several experiments and analyses to improve those limitations. We review the theory of optomechanical force sensing to understand the influence of optical radiation pressure on the dynamics of mechanical oscillators. We analyze several modified Mach-Zehnder interferometers and show how radiation pressure can be a resource for quantum measurement, including by establishing a surprising optical spring effect in a cavity held on-resonance. The most developed proposal is for a phase-sensitive optomechanical amplifier to avoid the photodetection losses that may limit next-generation gravitational wave interferometers utilizing cryogenic silicon mirrors and \u22482000 nm infrared lasers. The amplifier calls for high quality mechanical oscillators made of single crystal silicon, which we fabricate. We describe our efforts to develop a testbed for cryogenic mechanical loss measurements of silicon oscillators and thin film coatings. And, we show how Bayesian inference can be used to improve our understanding of the physical mechanisms limiting a system\u2019s mechanical loss. Finally, we describe the optical, mechanical, and electronic design of a prototype phase sensitive optomechanical amplifier. The prototype is useful for testing the control system required to implement the full amplifier, and we characterize the current control scheme and the scheme for near-term upgrades. Our latest measurements show a clear path to steadily improving the amplifier\u2019s noise figure with well understood technology.", "doi": "10.7907/wnm8-nb48", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:14579", "collection": "thesis", "collection_id": "14579", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05152022-181826611", "type": "thesis", "title": "Microwave-to-Optical Transduction Using Rare-Earth Ions", "author": [ { "family_name": "Rochman", "given_name": "Jake Herschel Lebi", "orcid": "0000-0002-8475-3389", "clpid": "Rochman-Jake-Herschel-Lebi" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Painter", "given_name": "Oskar J.", "orcid": "0000-0002-1581-9209", "clpid": "Painter-O" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Schwab", "given_name": "Keith C.", "orcid": "0000-0001-8216-4815", "clpid": "Schwab-K-C" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "Institute for Quantum Information and Matter" }, { "literal": "div_eng" } ], "abstract": "Superconducting qubits that operate at microwave frequencies are one of the most promising platforms for quantum information processing. However, connecting distant processors with microwave photons is challenging since microwave photons suffer from thermal noise and large propagation losses in room temperature components.
\r\n\r\nConversely, optical photons within the telecommunications band are known to have extremely low loss in optical fiber and the thermal noise is minuscule at room temperature. In order to interface superconducting qubits with room temperature optical photons, a quantum transducer is required that can convert photons between microwave and optical frequencies.
\r\n\r\nThis thesis describes the development of a microwave-to-optical transducer using an ensemble of erbium ions, doped within a yttrium orthovanadate crystal, that are simultaneously coupled to a superconducting microwave resonator and a photonic crystal optical resonator. The erbium ions have spin transitions that couple to the microwave resonator and optical transitions at telecom wavelengths that couple to the optical resonator.
", "doi": "10.7907/4h2f-wj87", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14593", "collection": "thesis", "collection_id": "14593", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05202022-191221394", "type": "thesis", "title": "Traveling Wave Parametric Amplifiers and Other Nonlinear Kinetic Inductance Devices", "author": [ { "family_name": "Klimovich", "given_name": "Nikita Sergeevich", "orcid": "0000-0002-5401-8260", "clpid": "Klimovich-Nikita-Sergeevich" } ], "thesis_advisor": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" }, { "family_name": "Day", "given_name": "Peter K.", "clpid": "Day-Peter-K" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The microwave frequency range is home to a large amount of cosmologically crucial signals including the cosmic microwave background, emission from high redshift galaxies, and spectral absorption from interstellar dust. In addition to this wealth of scientifically interesting signals, various cutting-edge detector technologies such as microwave kinetic inductance detectors also operate at those frequencies. Both of these areas would greatly benefit from improved readout electronics, which would ideally include broadband, high gain, and low noise amplification. These conditions are generally quite difficult to achieve simultaneously, and have driven the development of a large number of innovative technological solutions. Recently, superconducting traveling wave parametric amplifiers have emerged as a promising candidate for simultaneously meeting the amplification requirements in the microwave regime.
\r\n\r\nIn this thesis, we present further developments of traveling wave parametric amplifiers and other devices based on the nonlinear kinetic inductance of NbTiN transmission lines. The design techniques used for dispersion engineering and impedance matching are very robust, allowing for straightforward alterations to produce amplifiers with bandwidths centered at vastly different frequencies. The majority of our designs focus on the low frequency region from 2 to 12 GHz, where we demonstrate broadband amplifiers with 20 to 30 dB gain, quantum-limited noise, and minimal losses enabling vacuum noise squeezing. The excellent gain and noise performance of one such amplifier is further demonstrated by its use in the readout of a hidden photon dark matter search that sets new limits on the allowable kinetic mixing coupling. One such device was also operated in an up-conversion mode to demonstrate nearly perfect photon conversion efficiency of a narrowband signal near 1.75 GHz to a 12.55 GHz output. At higher frequencies, similar devices are shown to produce gain across over three octaves of bandwidth extending up to 34 GHz and a parametric amplifier operating in the W band. Utilizing the change in phase velocity in our transmission lines with applied current, we build and test a Fourier transform interferometer. We further present a smaller, optimized design that could someday enable the construction of a single-wafer kilopixel array of spectrometers for spatially resolved measurements of the spectral distortions in the cosmic microwave background.
", "doi": "10.7907/w980-rs97", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14593", "collection": "thesis", "collection_id": "14593", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05202022-191221394", "type": "thesis", "title": "Traveling Wave Parametric Amplifiers and Other Nonlinear Kinetic Inductance Devices", "author": [ { "family_name": "Klimovich", "given_name": "Nikita Sergeevich", "orcid": "0000-0002-5401-8260", "clpid": "Klimovich-Nikita-Sergeevich" } ], "thesis_advisor": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "orcid": "0000-0002-1098-7174", "clpid": "Golwala-S-R" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "orcid": "0000-0002-3330-5439", "clpid": "Zmuidzinas-J" }, { "family_name": "Day", "given_name": "Peter K.", "clpid": "Day-Peter-K" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "The microwave frequency range is home to a large amount of cosmologically crucial signals including the cosmic microwave background, emission from high redshift galaxies, and spectral absorption from interstellar dust. In addition to this wealth of scientifically interesting signals, various cutting-edge detector technologies such as microwave kinetic inductance detectors also operate at those frequencies. Both of these areas would greatly benefit from improved readout electronics, which would ideally include broadband, high gain, and low noise amplification. These conditions are generally quite difficult to achieve simultaneously, and have driven the development of a large number of innovative technological solutions. Recently, superconducting traveling wave parametric amplifiers have emerged as a promising candidate for simultaneously meeting the amplification requirements in the microwave regime.
\r\n\r\nIn this thesis, we present further developments of traveling wave parametric amplifiers and other devices based on the nonlinear kinetic inductance of NbTiN transmission lines. The design techniques used for dispersion engineering and impedance matching are very robust, allowing for straightforward alterations to produce amplifiers with bandwidths centered at vastly different frequencies. The majority of our designs focus on the low frequency region from 2 to 12 GHz, where we demonstrate broadband amplifiers with 20 to 30 dB gain, quantum-limited noise, and minimal losses enabling vacuum noise squeezing. The excellent gain and noise performance of one such amplifier is further demonstrated by its use in the readout of a hidden photon dark matter search that sets new limits on the allowable kinetic mixing coupling. One such device was also operated in an up-conversion mode to demonstrate nearly perfect photon conversion efficiency of a narrowband signal near 1.75 GHz to a 12.55 GHz output. At higher frequencies, similar devices are shown to produce gain across over three octaves of bandwidth extending up to 34 GHz and a parametric amplifier operating in the W band. Utilizing the change in phase velocity in our transmission lines with applied current, we build and test a Fourier transform interferometer. We further present a smaller, optimized design that could someday enable the construction of a single-wafer kilopixel array of spectrometers for spatially resolved measurements of the spectral distortions in the cosmic microwave background.
", "doi": "10.7907/w980-rs97", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14193", "collection": "thesis", "collection_id": "14193", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05282021-182147719", "type": "thesis", "title": "Novel Light-Matter Interaction in Quasi-One-Dimensional Graphene Nanomaterials for Photonics", "author": [ { "family_name": "Kishore Kumar", "given_name": "Deepan", "orcid": "0000-0003-0236-8805", "clpid": "Kishore-Kumar-Deepan" } ], "thesis_advisor": [ { "family_name": "Yeh", "given_name": "Nai-Chang", "orcid": "0000-0002-1826-419X", "clpid": "Yeh-Nai-Chang" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Yariv", "given_name": "Amnon", "clpid": "Yariv-A" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Yeh", "given_name": "Nai-Chang", "orcid": "0000-0002-1826-419X", "clpid": "Yeh-Nai-Chang" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Nonlinear light-matter interaction in two-dimensional (2D) materials like graphene with unique nanostructured quasi-one-dimensionality (quasi-1D) holds the potential to address major technology opportunities in photonics from on-chip photo detection, modulation of light, and even possibly coherent light sources. In this work, we propose to use graphene, a gapless two-dimensional nanomaterial, for both nano-photonic applications and potentially energy harvesting by nano-structuring the material into nearly quasi-one-dimensional effective optical cavities with defects that act like color centers. These defects are naturally formed during its synthesis or can be engineered in the material by selective plasma radiation, is found to support a broad spectral distribution of color centers that exhibit excitation dependent photoluminescence. Through detailed investigation on the temperature and power dependence of photoluminescence from such defects, excitation dependent photoluminescence emission, we have established that these graphene nanomaterials with metastable energy states can support material excitations (e.g., excitons) that are strongly coupled to the optical modes confined within the nanostructured cavities to produce polaritonic quasiparticles, leading to many interesting nonlinear behaviors. In particular, the manifestation of blue-shifted photoluminescence, polariton lasing-like emission, multimode lasing-like emission, and distinct interference fringes, all points to the presence of novel light-matter interaction in quasi-one-dimensional graphene. Such novel light matter interactions can be exploited, among other applications, within photonic integrated circuits (PIC) by directly synthesizing graphene on silicon from a low temperature, single-step, plasma-enhanced chemical vapor deposition (PECVD) with feedstock gases of methane and hydrogen.
", "doi": "10.7907/y5a2-zx57", "publication_date": "2021", "thesis_type": "phd", "thesis_year": "2021" }, { "id": "thesis:14193", "collection": "thesis", "collection_id": "14193", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05282021-182147719", "type": "thesis", "title": "Novel Light-Matter Interaction in Quasi-One-Dimensional Graphene Nanomaterials for Photonics", "author": [ { "family_name": "Kishore Kumar", "given_name": "Deepan", "orcid": "0000-0003-0236-8805", "clpid": "Kishore-Kumar-Deepan" } ], "thesis_advisor": [ { "family_name": "Yeh", "given_name": "Nai-Chang", "orcid": "0000-0002-1826-419X", "clpid": "Yeh-Nai-Chang" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Yariv", "given_name": "Amnon", "clpid": "Yariv-A" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Yeh", "given_name": "Nai-Chang", "orcid": "0000-0002-1826-419X", "clpid": "Yeh-Nai-Chang" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Nonlinear light-matter interaction in two-dimensional (2D) materials like graphene with unique nanostructured quasi-one-dimensionality (quasi-1D) holds the potential to address major technology opportunities in photonics from on-chip photo detection, modulation of light, and even possibly coherent light sources. In this work, we propose to use graphene, a gapless two-dimensional nanomaterial, for both nano-photonic applications and potentially energy harvesting by nano-structuring the material into nearly quasi-one-dimensional effective optical cavities with defects that act like color centers. These defects are naturally formed during its synthesis or can be engineered in the material by selective plasma radiation, is found to support a broad spectral distribution of color centers that exhibit excitation dependent photoluminescence. Through detailed investigation on the temperature and power dependence of photoluminescence from such defects, excitation dependent photoluminescence emission, we have established that these graphene nanomaterials with metastable energy states can support material excitations (e.g., excitons) that are strongly coupled to the optical modes confined within the nanostructured cavities to produce polaritonic quasiparticles, leading to many interesting nonlinear behaviors. In particular, the manifestation of blue-shifted photoluminescence, polariton lasing-like emission, multimode lasing-like emission, and distinct interference fringes, all points to the presence of novel light-matter interaction in quasi-one-dimensional graphene. Such novel light matter interactions can be exploited, among other applications, within photonic integrated circuits (PIC) by directly synthesizing graphene on silicon from a low temperature, single-step, plasma-enhanced chemical vapor deposition (PECVD) with feedstock gases of methane and hydrogen.
", "doi": "10.7907/y5a2-zx57", "publication_date": "2021", "thesis_type": "phd", "thesis_year": "2021" } ]