David Schuster

All Publications

• A cavity-array microscope for parallel single-atom interfacing. Nature Shaw, A. L., Soper, A., Shadmany, D., Kumar, A., Palm, L., Koh, D. Y., Kaxiras, V., Taneja, L., Jaffe, M., Schuster, D. I., Simon, J. 2026

  Abstract

  Neutral-atom arrays and optical cavity quantum electrodynamics systems have developed in parallel as central pillars of modern experimental quantum science1-3. Although each platform has shown exceptional capabilities-such as high-fidelity quantum logic4-7 in atom arrays and strong light-matter coupling in cavities8-10-their combination holds promise for realizing fast and non-destructive atom measurement11, building large-scale quantum networks12-17 and engineering hybrid atom-photon Hamiltonians18-20. However, so far, experiments integrating the two platforms have been limited to spatially interfacing the entire atom array with one global cavity mode21-26, a configuration that constrains addressability, parallelism and scalability. Here we introduce the cavity-array microscope, an experimental platform where each individual atom is strongly coupled to its own individual cavity across a two-dimensional array of over 40 modes. Our approach requires no nanophotonic elements26,27, and instead uses a free-space cavity geometry with intra-cavity lenses28,29 to realize above-unity peak cooperativity with micrometre-scale mode waists and spacings, compatible with typical atom-array length scales while keeping atoms far from dielectric surfaces. We achieve homogeneous atom-cavity coupling and show fast, non-destructive, parallel readout on millisecond timescales, including through a fibre array as a proof of principle for networking applications30. As an outlook, we realize a next-generation iteration of the platform with over 500 cavities and a nearly 10-fold improvement in finesse. Our work unlocks the regime of many-cavity quantum electrodynamics and opens an unexplored frontier of large-scale quantum networking with atom arrays.

  View details for DOI 10.1038/s41586-025-10035-9

  View details for PubMedID 41606334

  View details for PubMedCentralID 10567572

• Flux-Tunable Cavity for Dark Matter Detection. Physical review letters Zhao, F., Li, Z., Dixit, A. V., Roy, T., Vrajitoarea, A., Banerjee, R., Anferov, A., Lee, K. H., Schuster, D. I., Chou, A. 2025; 135 (20): 201002

  Abstract

  Developing a dark matter detector with wide mass tunability is an immensely desirable property, yet, it is challenging due to maintaining strong sensitivity. Resonant cavities for dark matter detection have traditionally employed mechanical tuning, moving parts around to change electromagnetic boundary conditions. However, these cavities have proven challenging to operate in sub-Kelvin cryogenic environments due to differential thermal contraction, low heat capacities, and low thermal conductivities. Instead, we develop an electronically tunable cavity architecture by coupling a superconducting 3D microwave cavity with a dc flux tunable superconducting quantum interference device. With a flux delivery system engineered to maintain high coherence in the cavity, we perform a hidden-photon dark matter search below the quantum-limited threshold. A microwave photon counting technique is employed through repeated quantum nondemolition measurements using a transmon qubit. With this device, we perform a hidden-photon search and constrain the kinetic mixing angle to ϵ<8.2×10^{-15} in a tunable band from 5.672 to 5.694 GHz. By coupling multimode tunable cavities to the transmon, wider hidden-photon searching ranges are possible.

  View details for DOI 10.1103/clp9-xc2n

  View details for PubMedID 41320532

• Implementation of a Quantum Addressable Router Using Superconducting Qubits PRX QUANTUM Miao, C., Leger, S., Li, Z., Lee, G., Jiang, L., Schuster, D. I. 2025; 6 (4)

  View details for DOI 10.1103/pq3x-cmw9

  View details for Web of Science ID 001617483600001

• Niobium coaxial cavities with internal quality factors exceeding 1.4 x 109 for circuit quantum electrodynamics PHYSICAL REVIEW APPLIED Oriani, A. E., Zhao, F., Roy, T., Anferov, A., He, K., Agrawal, A., Banerjee, R., Chakram, S., Schuster, D. I. 2025; 24 (4)

  View details for DOI 10.1103/ht5k-yb53

  View details for Web of Science ID 001616138900003

• Light-controlled strong coupling of optical cavity modes spaced by 200 THz OPTICS LETTERS Taneja, L., Schuster, D., Simon, J. 2025; 50 (18): 5698-5701

  Abstract

  Cavities have driven significant advances in optical physics and quantum science, with applications ranging from lasers and spectroscopy to quantum information processing, simulation, and metrology. For standard optical cavities, each eigenmode corresponds to a single, well-defined frequency. Here, we present a macroscopic optical Fabry-Pérot cavity whose eigenmodes are coherent superpositions of two frequency modes in the VIS-NIR range. Specifically, we demonstrate strong coupling between 384 THz (780 nm) and 580 THz (516 nm) cavity modes by incorporating an intracavity χ(2) crystal driven by a non-resonant optical pump at 1529 nm. Strong coupling enables us to demonstrate frequency conversion with an end-to-end, free-space conversion efficiency of 30(1)%, limited by current cavity design and internal cavity losses. We also demonstrate coupling between distinct spatial modes at the two frequencies, extending coherent control to the spatial basis. In conjunction with improved resonator design and low-loss non-linear crystals, we anticipate a factor of >50 increase in two-mode cooperativity for stronger coupling and near-unity conversion efficiency at low pump powers. This platform opens new avenues for cavity-QED experiments, with potential applications spanning cavity-mediated interactions between distinct atomic species, interconnects for quantum networking and modular computing, and spatially multimode cavity physics.

  View details for DOI 10.1364/OL.563882

  View details for Web of Science ID 001583032600004

  View details for PubMedID 40954859

• Millimeter-Wave Superconducting Qubit PRX QUANTUM Anferov, A., Wan, F., Harvey, S. P., Simon, J., Schuster, D. I. 2025; 6 (2)

  View details for DOI 10.1103/PRXQuantum.6.020336

  View details for Web of Science ID 001502330300001

• Cavity QED in a high NA resonator. Science advances Shadmany, D., Kumar, A., Soper, A., Palm, L., Yin, C., Ando, H., Li, B., Taneja, L., Jaffe, M., David, S., Simon, J. 2025; 11 (9): eads8171

  Abstract

  From fundamental studies of light-matter interaction to applications in quantum networking and sensing, cavity quantum electrodynamics (QED) provides a toolbox to control interactions between atoms and photons. The coherence of interactions is determined by the single-pass atomic absorption and number of photon round-trips. Reducing the cavity loss has enabled resonators supporting 1 million roundtrips but with limited material choices and increased alignment sensitivity. Here, we present a high-numerical aperture, lens-based resonator that pushes the single-atom single-photon absorption probability near its fundamental limit, reducing the mode size at the atom to order λ. This resonator provides a single-atom cooperativity of 1.6 in a cavity where the light circulates ∼10 times. We load single 87Rb atoms into this cavity, observe strong coupling, and demonstrate cavity-enhanced atom detection with fidelity of 99.55(6)% and survival of 99.89(4)% in 130 μs. Introducing intracavity imaging systems will enable cavity arrays compatible with Rydberg atom array computing technologies, expanding the applicability of the cavity QED toolbox.

  View details for DOI 10.1126/sciadv.ads8171

  View details for PubMedID 40009689

  View details for PubMedCentralID PMC11864187

• High-impedance resonators for strong coupling to an electron on helium PHYSICAL REVIEW APPLIED Koolstra, G., Glen, E. O., Beysengulov, N. R., Byeon, H., Castoria, K. E., Sammon, M., Dizdar, B., Wang, C. S., Schuster, D. I., Lyon, S. A., Pollanen, J., Rees, D. G. 2025; 23 (2)

  View details for DOI 10.1103/PhysRevApplied.23.024001

  View details for Web of Science ID 001436405200005

• High-Fidelity Two-Qubit Gates between Fluxonium Qubits with a Resonator Coupler PRX QUANTUM Rosenfeld, E. L., Hann, C. T., Schuster, D. I., Matheny, M. H., Clerk, A. A. 2024; 5 (4)

  View details for DOI 10.1103/PRXQuantum.5.040317

  View details for Web of Science ID 001350546700001

• Superconducting Qubits above 20 GHz Operating over 200 mK PRX QUANTUM Anferov, A., Harvey, S. P., Wan, F., Simon, J., Schuster, D. I. 2024; 5 (3)

  View details for DOI 10.1103/PRXQuantum.5.030347

  View details for Web of Science ID 001314055000001

• Autonomous stabilization with programmable stabilized state. Nature communications Li, Z., Roy, T., Lu, Y., Kapit, E., Schuster, D. I. 2024; 15 (1): 6978

  Abstract

  Reservoir engineering is a powerful technique to autonomously stabilize a quantum state. Traditional schemes involving multi-body states typically function for discrete entangled states. In this work, we enhance the stabilization capability to a continuous manifold of states with programmable stabilized state selection using multiple continuous tuning parameters. We experimentally achieve 84.6% and 82.5% stabilization fidelity for the odd and even-parity Bell states as two special points in the manifold. We also perform fast dissipative switching between these opposite parity states within 1.8 μs and 0.9 μs by sequentially applying different stabilization drives. Our result is a precursor for new reservoir engineering-based error correction schemes.

  View details for DOI 10.1038/s41467-024-51262-4

  View details for PubMedID 39143062

  View details for PubMedCentralID PMC11324797

• Manybody interferometry of quantum fluids. Science advances Roberts, G., Vrajitoarea, A., Saxberg, B., Panetta, M. G., Simon, J., Schuster, D. I. 2024; 10 (29): eado1069

  Abstract

  Characterizing strongly correlated matter is an increasingly central challenge in quantum science, where structure is often obscured by massive entanglement. It is becoming clear that in the quantum regime, state preparation and characterization should not be treated separately-entangling the two processes provides a quantum advantage in information extraction. Here, we present an approach that we term "manybody Ramsey interferometry" that combines adiabatic state preparation and Ramsey spectroscopy: Leveraging our recently developed one-to-one mapping between computational-basis states and manybody eigenstates, we prepare a superposition of manybody eigenstates controlled by the state of an ancilla qubit, allow the superposition to evolve relative phase, and then reverse the preparation protocol to disentangle the ancilla while localizing phase information back into it. Ancilla tomography then extracts information about the manybody eigenstates, the associated excitation spectrum, and thermodynamic observables. This work illustrates the potential for using quantum computers to efficiently probe quantum matter.

  View details for DOI 10.1126/sciadv.ado1069

  View details for PubMedID 39028806

  View details for PubMedCentralID PMC11259156

• Efficient multimode Wigner tomography. Nature communications He, K., Yuan, M., Wong, Y., Chakram, S., Seif, A., Jiang, L., Schuster, D. I. 2024; 15 (1): 4138

  Abstract

  Advancements in quantum system lifetimes and control have enabled the creation of increasingly complex quantum states, such as those on multiple bosonic cavity modes. When characterizing these states, traditional tomography scales exponentially with the number of modes in both computational and experimental measurement requirement, which becomes prohibitive as the system size increases. Here, we implement a state reconstruction method whose sampling requirement instead scales polynomially with system size, and thus mode number, for states that can be represented within such a polynomial subspace. We demonstrate this improved scaling with Wigner tomography of multimode entangled W states of up to 4 modes on a 3D circuit quantum electrodynamics (cQED) system. This approach performs similarly in efficiency to existing matrix inversion methods for 2 modes, and demonstrates a noticeable improvement for 3 and 4 modes, with even greater theoretical gains at higher mode numbers.

  View details for DOI 10.1038/s41467-024-48573-x

  View details for PubMedID 38755182

• Tunable Inductive Coupler for High-Fidelity Gates Between Fluxonium Qubits PRX QUANTUM Zhang, H., Ding, C., Weiss, D. K., Huang, Z., Ma, Y., Guinn, C., Sussman, S., Chitta, S., Chen, D., Houck, A. A., Koch, J., Schuster, D. I. 2024; 5 (2)

  View details for DOI 10.1103/PRXQuantum.5.020326

  View details for Web of Science ID 001222974900001

• Stimulated Emission of Signal Photons from Dark Matter Waves. Physical review letters Agrawal, A., Dixit, A. V., Roy, T., Chakram, S., He, K., Naik, R. K., Schuster, D. I., Chou, A. 2024; 132 (14): 140801

  Abstract

  The manipulation of quantum states of light has resulted in significant advancements in both dark matter searches and gravitational wave detectors. Current dark matter searches operating in the microwave frequency range use nearly quantum-limited amplifiers. Future high frequency searches will use photon counting techniques to evade the standard quantum limit. We present a signal enhancement technique that utilizes a superconducting qubit to prepare a superconducting microwave cavity in a nonclassical Fock state and stimulate the emission of a photon from a dark matter wave. By initializing the cavity in an |n=4⟩ Fock state, we demonstrate a quantum enhancement technique that increases the signal photon rate and hence also the dark matter scan rate each by a factor of 2.78. Using this technique, we conduct a dark photon search in a band around 5.965 GHz (24.67  μeV), where the kinetic mixing angle ε≥4.35×10^{-13} is excluded at the 90% confidence level.

  View details for DOI 10.1103/PhysRevLett.132.140801

  View details for PubMedID 38640371

• Experimental advances with the QICK (Quantum Instrumentation Control Kit) for superconducting quantum hardware PHYSICAL REVIEW RESEARCH Ding, C., Di Federico, M., Hatridge, M., Houck, A., Leger, S., Martinez, J., Miao, C., Schuster, D., Stefanazzi, L., Stoughton, C., Sussman, S., Treptow, K., Uemura, S., Wilcer, N., Zhang, H., Zhou, C., Cancelo, G. 2024; 6 (1)

  View details for DOI 10.1103/PhysRevResearch.6.013305

  View details for Web of Science ID 001196435000001

• Improved coherence in optically defined niobium trilayer-junction qubits PHYSICAL REVIEW APPLIED Anferov, A., Lee, K., Zhao, F., Simon, J., Schuster, D. I. 2024; 21 (2)

  View details for DOI 10.1103/PhysRevApplied.21.024047

  View details for Web of Science ID 001187567700003

• Autonomous error correction of a single logical qubit using two transmons. Nature communications Li, Z., Roy, T., Rodríguez Pérez, D., Lee, K. H., Kapit, E., Schuster, D. I. 2024; 15 (1): 1681

  Abstract

  Large-scale quantum computers will inevitably need quantum error correction to protect information against decoherence. Traditional error correction typically requires many qubits, along with high-efficiency error syndrome measurement and real-time feedback. Autonomous quantum error correction instead uses steady-state bath engineering to perform the correction in a hardware-efficient manner. In this work, we develop a new autonomous quantum error correction scheme that actively corrects single-photon loss and passively suppresses low-frequency dephasing, and we demonstrate an important experimental step towards its full implementation with transmons. Compared to uncorrected encoding, improvements are experimentally witnessed for the logical zero, one, and superposition states. Our results show the potential of implementing hardware-efficient autonomous quantum error correction to enhance the reliability of a transmon-based quantum information processor.

  View details for DOI 10.1038/s41467-024-45858-z

  View details for PubMedID 38395989

  View details for PubMedCentralID PMC10891116

• Hardware-efficient autonomous error correction with linear couplers in superconducting circuits PHYSICAL REVIEW RESEARCH Li, Z., Roy, T., Perez, D., Schuster, D. I., Kapit, E. 2024; 6 (1)

  View details for DOI 10.1103/PhysRevResearch.6.013171

  View details for Web of Science ID 001170856400001

• Electron charge qubit with 0.1 millisecond coherence time NATURE PHYSICS Zhou, X., Li, X., Chen, Q., Koolstra, G., Yang, G., Dizdar, B., Huang, Y., Wang, C. S., Han, X., Zhang, X., Schuster, D. I., Jin, D. 2024; 20 (1): 116-+

  View details for DOI 10.1038/s41567-023-02247-5

  View details for Web of Science ID 001658095700003

• Exploring ququart computation on a transmon using optimal control PHYSICAL REVIEW A Seifert, L., Li, Z., Roy, T., Schuster, D. I., Chong, F. T., Baker, J. M. 2023; 108 (6)

  View details for DOI 10.1103/PhysRevA.108.062609

  View details for Web of Science ID 001156769200008

• Two-Qutrit Quantum Algorithms on a Programmable Superconducting PHYSICAL REVIEW APPLIED Roy, T., Li, Z., Kapit, E., Schuster, D. 2023; 19 (6)

  View details for DOI 10.1103/PhysRevApplied.19.064024

  View details for Web of Science ID 001015815300004

• Quantum-enabled millimetre wave to optical transduction using neutral atoms. Nature Kumar, A., Suleymanzade, A., Stone, M., Taneja, L., Anferov, A., Schuster, D. I., Simon, J. 2023; 615 (7953): 614-619

  Abstract

  Early experiments with transiting circular Rydberg atoms in a superconducting resonator laid the foundations of modern cavity and circuit quantum electrodynamics1, and helped explore the defining features of quantum mechanics such as entanglement. Whereas ultracold atoms and superconducting circuits have since taken rather independent paths in the exploration of new physics, taking advantage of their complementary strengths in an integrated system enables access to fundamentally new parameter regimes and device capabilities2,3. Here we report on such a system, coupling an ensemble of cold 85Rb atoms simultaneously to an, as far as we are aware, first-of-its-kind optically accessible, three-dimensional superconducting resonator4 and a vibration-suppressed optical cavity in a cryogenic (5 K) environment. To demonstrate the capabilities of this platform, and with an eye towards quantum networking5, we leverage the strong coupling between Rydberg atoms and the superconducting resonator to implement a quantum-enabled millimetre wave (mmwave) photon to optical photon transducer6. We measured an internal conversion efficiency of 58(11)%, a conversion bandwidth of 360(20) kHz and added thermal noise of 0.6 photons, in agreement with a parameter-free theory. Extensions of this technique will allow near-unity efficiency transduction in both the mmwave and microwave regimes. More broadly, our results open a new field of hybrid mmwave/optical quantum science, with prospects for operation deep in the strong coupling regime for efficient generation of metrologically or computationally useful entangled states7 and quantum simulation/computation with strong non-local interactions8.

  View details for DOI 10.1038/s41586-023-05740-2

  View details for PubMedID 36949338

  View details for PubMedCentralID 4386362

• Error-Divisible Two-Qubit Gates PHYSICAL REVIEW APPLIED Perez, D., Varosy, P., Li, Z., Roy, T., Kapit, E., Schuster, D. 2023; 19 (2)

  View details for DOI 10.1103/PhysRevApplied.19.024043

  View details for Web of Science ID 000936528900004

• Dancing the Quantum Waltz: Compiling Three-Qubit Gates on Four Level Architectures Litteken, A., Seifert, L., Chadwick, J. D., Nottingham, N., Roy, T., Li, Z., Schuster, D., Chong, F. T., Baker, J. M., ACM ASSOC COMPUTING MACHINERY. 2023: 992-1005

  View details for DOI 10.1145/3579371.3589106

  View details for Web of Science ID 001098723900071

• Fast High-Fidelity Gates for Galvanically-Coupled Fluxonium Qubits Using Strong Flux Modulation PRX QUANTUM Weiss, D. K., Zhang, H., Ding, C., Ma, Y., Schuster, D. I., Koch, J. 2022; 3 (4)

  View details for DOI 10.1103/PRXQuantum.3.040336

  View details for Web of Science ID 000912782600001

• Disorder-assisted assembly of strongly correlated fluids of light. Nature Saxberg, B., Vrajitoarea, A., Roberts, G., Panetta, M. G., Simon, J., Schuster, D. I. 2022; 612 (7940): 435-441

  Abstract

  Guiding many-body systems to desired states is a central challenge of modern quantum science, with applications from quantum computation1,2 to many-body physics3 and quantum-enhanced metrology4. Approaches to solving this problem include step-by-step assembly5,6, reservoir engineering to irreversibly pump towards a target state7,8 and adiabatic evolution from a known initial state9,10. Here we construct low-entropy quantum fluids of light in a Bose-Hubbard circuit by combining particle-by-particle assembly and adiabatic preparation. We inject individual photons into a disordered lattice for which the eigenstates are known and localized, then adiabatically remove this disorder, enabling quantum fluctuations to melt the photons into a fluid. Using our platform11, we first benchmark this lattice melting technique by building and characterizing arbitrary single-particle-in-a-box states, then assemble multiparticle strongly correlated fluids. Intersite entanglement measurements performed through single-site tomography indicate that the particles in the fluid delocalize, whereas two-body density correlation measurements demonstrate that they also avoid one another, revealing Friedel oscillations characteristic of a Tonks-Girardeau gas12,13. This work opens new possibilities for the preparation of topological and otherwise exotic phases of synthetic matter3,14,15.

  View details for DOI 10.1038/s41586-022-05357-x

  View details for PubMedID 36517711

• Chiral cavity quantum electrodynamics NATURE PHYSICS Owens, J., Panetta, M. G., Saxberg, B., Roberts, G., Chakram, S., Ma, R., Vrajitoarea, A., Simon, J., Schuster, D. 2022; 18 (9): 1048-+

  View details for DOI 10.1038/s41567-022-01671-3

  View details for Web of Science ID 000832510400002

• Multimode photon blockade NATURE PHYSICS Chakram, S., He, K., Dixit, A., Oriani, A. E., Naik, R. K., Leung, N., Kwon, H., Ma, W., Jiang, L., Schuster, D. 2022; 18 (8): 879-+

  View details for DOI 10.1038/s41567-022-01630-y

  View details for Web of Science ID 000814946000003

• Single electrons on solid neon as a solid-state qubit platform NATURE Zhou, X., Koolstra, G., Zhang, X., Yang, G., Han, X., Dizdar, B., Li, X., Divan, R., Guo, W., Murch, K. W., Schuster, D. I., Jin, D. 2022; 605 (7908): 46-+

  Abstract

  Progress towards the realization of quantum computers requires persistent advances in their constituent building blocks-qubits. Novel qubit platforms that simultaneously embody long coherence, fast operation and large scalability offer compelling advantages in the construction of quantum computers and many other quantum information systems1-3. Electrons, ubiquitous elementary particles of non-zero charge, spin and mass, have commonly been perceived as paradigmatic local quantum information carriers. Despite superior controllability and configurability, their practical performance as qubits through either motional or spin states depends critically on their material environment3-5. Here we report our experimental realization of a qubit platform based on isolated single electrons trapped on an ultraclean solid neon surface in vacuum6-13. By integrating an electron trap in a circuit quantum electrodynamics architecture14-20, we achieve strong coupling between the motional states of a single electron and a single microwave photon in an on-chip superconducting resonator. Qubit gate operations and dispersive readout are implemented to measure the energy relaxation time T1 of 15 μs and phase coherence time T2 over 200 ns. These results indicate that the electron-on-solid-neon qubit already performs near the state of the art for a charge qubit21.

  View details for DOI 10.1038/s41586-022-04539-x

  View details for Web of Science ID 000790960500012

  View details for PubMedID 35508782

  View details for PubMedCentralID 6874564

• Deterministic Grover search with a restricted oracle PHYSICAL REVIEW RESEARCH Roy, T., Jiang, L., Schuster, D. 2022; 4 (2)

  View details for DOI 10.1103/PhysRevResearch.4.L022013

  View details for Web of Science ID 000798376900001

• The QICK (Quantum Instrumentation Control Kit): Readout and control for qubits and detectors REVIEW OF SCIENTIFIC INSTRUMENTS Stefanazzi, L., Treptow, K., Wilcer, N., Stoughton, C., Bradford, C., Uemura, S., Zorzetti, S., Montella, S., Cancelo, G., Sussman, S., Houck, A., Saxena, S., Arnaldi, H., Agrawal, A., Zhang, H., Ding, C., Schuster, D. 2022; 93 (4)

  View details for DOI 10.1063/5.0076249

  View details for Web of Science ID 000793160400004

• Robust Quantum Optimal Control with Trajectory Optimization PHYSICAL REVIEW APPLIED Propson, T., Jackson, B. E., Koch, J., Manchester, Z., Schuster, D. I. 2022; 17 (1)

  View details for DOI 10.1103/PhysRevApplied.17.014036

  View details for Web of Science ID 000748572300003

• Moving beyond the Transmon: Noise-Protected Superconducting Quantum Circuits PRX QUANTUM Gyenis, A., Di Paolo, A., Koch, J., Blais, A., Houck, A. A., Schuster, D. 2021; 2 (3)

  View details for DOI 10.1103/PRXQuantum.2.030101

  View details for Web of Science ID 000692803300001

• Seamless High-<i>Q</i> Microwave Cavities for Multimode Circuit Quantum Electrodynamics PHYSICAL REVIEW LETTERS Chakram, S., Oriani, A. E., Naik, R. K., Dixit, A. V., He, K., Agrawal, A., Kwon, H., Schuster, D. I. 2021; 127 (10): 107701

  Abstract

  Multimode cavity quantum electrodynamics-where a two-level system interacts simultaneously with many cavity modes-provides a versatile framework for quantum information processing and quantum optics. Because of the combination of long coherence times and large interaction strengths, one of the leading experimental platforms for cavity QED involves coupling a superconducting circuit to a 3D microwave cavity. In this work, we realize a 3D multimode circuit QED system with single photon lifetimes of 2 ms across 9 modes of a novel seamless cavity. We demonstrate a variety of protocols for universal single-mode quantum control applicable across all cavity modes, using only a single drive line. We achieve this by developing a straightforward flute method for creating monolithic superconducting microwave cavities that reduces loss while simultaneously allowing control of the mode spectrum and mode-qubit interaction. We highlight the flexibility and ease of implementation of this technique by using it to fabricate a variety of 3D cavity geometries, providing a template for engineering multimode quantum systems with exceptionally low dissipation. This work is an important step towards realizing hardware efficient random access quantum memories and processors, and for exploring quantum many-body physics with photons.

  View details for DOI 10.1103/PhysRevLett.127.107701

  View details for Web of Science ID 000692200800022

  View details for PubMedID 34533363

• Searching for Dark Matter with a Superconducting Qubit PHYSICAL REVIEW LETTERS Dixit, A., Chakram, S., He, K., Agrawal, A., Naik, R. K., Schuster, D., Chou, A. 2021; 126 (14): 141302

  Abstract

  Detection mechanisms for low mass bosonic dark matter candidates, such as the axion or hidden photon, leverage potential interactions with electromagnetic fields, whereby the dark matter (of unknown mass) on rare occasion converts into a single photon. Current dark matter searches operating at microwave frequencies use a resonant cavity to coherently accumulate the field sourced by the dark matter and a near standard quantum limited (SQL) linear amplifier to read out the cavity signal. To further increase sensitivity to the dark matter signal, sub-SQL detection techniques are required. Here we report the development of a novel microwave photon counting technique and a new exclusion limit on hidden photon dark matter. We operate a superconducting qubit to make repeated quantum nondemolition measurements of cavity photons and apply a hidden Markov model analysis to reduce the noise to 15.7 dB below the quantum limit, with overall detector performance limited by a residual background of real photons. With the present device, we perform a hidden photon search and constrain the kinetic mixing angle to ε≤1.68×10^{-15} in a band around 6.011 GHz (24.86  μeV) with an integration time of 8.33 s. This demonstrated noise reduction technique enables future dark matter searches to be sped up by a factor of 1,300. By coupling a qubit to an arbitrary quantum sensor, more general sub-SQL metrology is possible with the techniques presented in this Letter.

  View details for DOI 10.1103/PhysRevLett.126.141302

  View details for Web of Science ID 000652827800004

  View details for PubMedID 33891438

• Engineering Dynamical Sweet Spots to Protect Qubits from 1/f Noise PHYSICAL REVIEW APPLIED Huang, Z., Mundada, P. S., Gyenis, A., Schuster, D., Houck, A. A., Koch, J. 2021; 15 (3)

  View details for DOI 10.1103/PhysRevApplied.15.034065

  View details for Web of Science ID 000669960000002

• Experimental Realization of a Protected Superconducting Circuit Derived from the 0-π Qubit PRX QUANTUM Gyenis, A., Mundada, P. S., Di Paolo, A., Hazard, T. M., You, X., Schuster, D., Koch, J., Blais, A., Houck, A. A. 2021; 2 (1)

  View details for DOI 10.1103/PRXQuantum.2.010339

  View details for Web of Science ID 000674695000001

• Deterministic multi-qubit entanglement in a quantum network NATURE Zhong, Y., Chang, H., Bienfait, A., Dumur, E., Chou, M., Conner, C. R., Grebel, J., Povey, R. G., Yan, H., Schuster, D., Cleland, A. N. 2021; 590 (7847): 571-575

  Abstract

  The generation of high-fidelity distributed multi-qubit entanglement is a challenging task for large-scale quantum communication and computational networks1-4. The deterministic entanglement of two remote qubits has recently been demonstrated with both photons5-10 and phonons11. However, the deterministic generation and transmission of multi-qubit entanglement has not been demonstrated, primarily owing to limited state-transfer fidelities. Here we report a quantum network comprising two superconducting quantum nodes connected by a one-metre-long superconducting coaxial cable, where each node includes three interconnected qubits. By directly connecting the cable to one qubit in each node, we transfer quantum states between the nodes with a process fidelity of 0.911 ± 0.008. We also prepare a three-qubit Greenberger-Horne-Zeilinger (GHZ) state12-14 in one node and deterministically transfer this state to the other node, with a transferred-state fidelity of 0.656 ± 0.014. We further use this system to deterministically generate a globally distributed two-node, six-qubit GHZ state with a state fidelity of 0.722 ± 0.021. The GHZ state fidelities are clearly above the threshold of 1/2 for genuine multipartite entanglement15, showing that this architecture can be used to coherently link together multiple superconducting quantum processors, providing a modular approach for building large-scale quantum computers16,17.

  View details for DOI 10.1038/s41586-021-03288-7

  View details for Web of Science ID 000621583600007

  View details for PubMedID 33627810

• Universal Fast-Flux Control of a Coherent, Low-Frequency Qubit PHYSICAL REVIEW X Zhang, H., Chakram, S., Roy, T., Earnest, N., Lu, Y., Huang, Z., Koch, J., Schuster, D., Weiss, D. K. 2021; 11 (1)

  View details for DOI 10.1103/PhysRevX.11.011010

  View details for Web of Science ID 000608184100001

• Optical mode conversion in coupled Fabry-Perot resonators OPTICS LETTERS Stone, M., Suleymanzade, A., Taneja, L., Schuster, D., Simon, J. 2021; 46 (1): 21-24

  Abstract

  Low-loss conversion among a complete and orthogonal set of optical modes is important for high-bandwidth quantum and classical communication. In this Letter, we explore tunable impedance mismatch between coupled Fabry-Perot resonators as a powerful tool for manipulation of the spatial and temporal properties of optical fields. In the single-mode regime, frequency-dependent impedance matching enables tunable finesse optical resonators. Introducing the spatial dependence of the impedance mismatch enables coherent spatial mode conversion of optical photons at near-unity efficiency. We experimentally demonstrate a NIR resonator whose finesse is tunable over a decade, and an optical mode converter with efficiency >75% for the first six Hermite-Gauss modes. We anticipate that this new perspective on coupled multimode resonators will have exciting applications in micro- and nano-photonics and computer-aided inverse design.

  View details for DOI 10.1364/OL.400998

  View details for Web of Science ID 000603399900006

  View details for PubMedID 33362003

• Resource-Efficient Quantum Computing by Breaking Abstractions PROCEEDINGS OF THE IEEE Shi, Y., Gokhale, P., Murali, P., Baker, J. M., Duckering, C., Ding, Y., Brown, N. C., Chamberland, C., Javadi-Abhari, A., Cross, A. W., Schuster, D., Brown, K. R., Martonosi, M., Chong, F. T. 2020; 108 (8): 1353-1370

  View details for DOI 10.1109/JPROC.2020.2994765

  View details for Web of Science ID 000550650500010

• A tunable high-Q millimeter wave cavity for hybrid circuit and cavity QED experiments APPLIED PHYSICS LETTERS Suleymanzade, A., Anferov, A., Stone, M., Naik, R. K., Oriani, A., Simon, J., Schuster, D. 2020; 116 (10)

  View details for DOI 10.1063/1.5137900

  View details for Web of Science ID 000520496500001

• Photonic materials in circuit quantum electrodynamics NATURE PHYSICS Carusotto, I., Houck, A. A., Kollar, A. J., Roushan, P., Schuster, D. I., Simon, J. 2020; 16 (3): 268-279

  View details for DOI 10.1038/s41567-020-0815-y

  View details for Web of Science ID 000517742600004

• Millimeter-Wave Four-Wave Mixing via Kinetic Inductance for Quantum Devices PHYSICAL REVIEW APPLIED Anferov, A., Suleymanzade, A., Oriani, A., Simon, J., Schuster, D. I. 2020; 13 (2)

  View details for DOI 10.1103/PhysRevApplied.13.024056

  View details for Web of Science ID 000515064100002

• Universal gates for protected superconducting qubits using optimal control PHYSICAL REVIEW A Abdelhafez, M., Baker, B., Gyenis, A., Mundada, P., Houck, A. A., Schuster, D., Koch, J. 2020; 101 (2)

  View details for DOI 10.1103/PhysRevA.101.022321

  View details for Web of Science ID 000514173800006

• Memory-Equipped Quantum Architectures: The Power of Random Access Baker, J. M., Schuster, D., Chong, F. T., ASSOC COMP MACHINERY ASSOC COMPUTING MACHINERY. 2020: 387-398

  View details for DOI 10.1145/3410463.3414644

  View details for Web of Science ID 000723645400042

• Virtualized Logical Qubits: A 2.5D Architecture for Error-Corrected Quantum Computing Duckering, C., Baker, J. M., Schuster, D., Chong, F. T., IEEE COMP SOC IEEE COMPUTER SOC. 2020: 173-185

  View details for DOI 10.1109/MICRO50266.2020.00026

  View details for Web of Science ID 000792639000013

• A nonlinear, geometric Hall effect without magnetic field PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Schade, N. B., Schuster, D. I., Nagel, S. R. 2019; 116 (49): 24475-24479

  Abstract

  The classical Hall effect, the traditional means of determining charge-carrier sign and density in a conductor, requires a magnetic field to produce transverse voltages across a current-carrying wire. We demonstrate a use of geometry to create transverse potentials along curved paths without any magnetic field. These potentials also reflect the charge-carrier sign and density. We demonstrate this effect experimentally in curved wires where the transverse potentials are consistent with the doping and change polarity as we switch the carrier sign. In straight wires, we measure transverse potential fluctuations with random polarity demonstrating that the current follows a complex, tortuous path. This geometrically induced potential offers a sensitive characterization of inhomogeneous current flow in thin films.

  View details for DOI 10.1073/pnas.1916406116

  View details for Web of Science ID 000500804600022

  View details for PubMedID 31740619

  View details for PubMedCentralID PMC6900534

• Coupling a single electron on superfluid helium to a superconducting resonator NATURE COMMUNICATIONS Koolstra, G., Yang, G., Schuster, D. 2019; 10: 5323

  Abstract

  Electrons on helium form a unique two-dimensional system on the interface of liquid helium and vacuum. A small number of trapped electrons on helium exhibits strong interactions in the absence of disorder, and can be used as a qubit. Trapped electrons typically have orbital frequencies in the microwave regime and can therefore be integrated with circuit quantum electrodynamics (cQED), which studies light-matter interactions using microwave photons. Here, we experimentally realize a cQED platform with the orbitals of single electrons on helium. We deterministically trap one to four electrons in a dot integrated with a microwave resonator, allowing us to study the electrons' response to microwaves. Furthermore, we find a single-electron-photon coupling strength of [Formula: see text] MHz, greatly exceeding the resonator linewidth [Formula: see text] MHz. These results pave the way towards microwave studies of Wigner molecules and coherent control of the orbital and spin state of a single electron on helium.

  View details for DOI 10.1038/s41467-019-13335-7

  View details for Web of Science ID 000498197400001

  View details for PubMedID 31757947

  View details for PubMedCentralID PMC6874564

• Two-Dimensional Material Tunnel Barrier for Josephson Junctions and Superconducting Qubits NANO LETTERS Lee, K., Chakram, S., Kim, S., Mujid, F., Ray, A., Gao, H., Park, C., Zhong, Y., Muller, D. A., Schuster, D. I., Park, J. 2019; 19 (11): 8287-8293

  Abstract

  Quantum computing based on superconducting qubits requires the understanding and control of the materials, device architecture, and operation. However, the materials for the central circuit element, the Josephson junction, have mostly been focused on using the AlOx tunnel barrier. Here, we demonstrate Josephson junctions and superconducting qubits employing two-dimensional materials as the tunnel barrier. We batch-fabricate and design the critical Josephson current of these devices via layer-by-layer stacking N layers of MoS2 on the large scale. Based on such junctions, MoS2 transmon qubits are engineered and characterized in a bulk superconducting microwave resonator for the first time. Our work allows Josephson junctions to access the diverse material properties of two-dimensional materials that include a wide range of electrical and magnetic properties, which can be used to study the effects of different material properties in superconducting qubits and to engineer novel quantum circuit elements in the future.

  View details for DOI 10.1021/acs.nanolett.9b03886

  View details for Web of Science ID 000497259300087

  View details for PubMedID 31661615

• Violating Bell's inequality with remotely connected superconducting qubits NATURE PHYSICS Zhong, Y. P., Chang, H., Satzinger, K. J., Chou, M., Bienfait, A., Conner, C. R., Dumur, E., Grebel, J., Peairs, G. A., Povey, R. G., Schuster, D. I., Cleland, A. N. 2019; 15 (8): 741-+

  View details for DOI 10.1038/s41567-019-0507-7

  View details for Web of Science ID 000478082100015

• Gradient-based optimal control of open quantum systems using quantum trajectories and automatic differentiation PHYSICAL REVIEW A Abdelhafez, M., Schuster, D., Koch, J. 2019; 99 (5)

  View details for DOI 10.1103/PhysRevA.99.052327

  View details for Web of Science ID 000469015400003

• Simple non-galvanic flip-chip integration method for hybrid quantum systems APPLIED PHYSICS LETTERS Satzinger, K. J., Conner, C. R., Bienfait, A., Chang, H., Chou, M., Cleland, A. Y., Dumur, E., Grebel, J., Peairs, G. A., Povey, R. G., Whiteley, S. J., Zhong, Y. P., Awschalom, D. D., Schuster, D., Cleland, A. N. 2019; 114 (17)

  View details for DOI 10.1063/1.5089888

  View details for Web of Science ID 000466889100027

• A dissipatively stabilized Mott insulator of photons NATURE Ma, R., Saxberg, B., Owens, C., Leung, N., Lu, Y., Simon, J., Schuster, D. I. 2019; 566 (7742): 51-57

  Abstract

  Superconducting circuits are a competitive platform for quantum computation because they offer controllability, long coherence times and strong interactions-properties that are essential for the study of quantum materials comprising microwave photons. However, intrinsic photon losses in these circuits hinder the realization of quantum many-body phases. Here we use superconducting circuits to explore strongly correlated quantum matter by building a Bose-Hubbard lattice for photons in the strongly interacting regime. We develop a versatile method for dissipative preparation of incompressible many-body phases through reservoir engineering and apply it to our system to stabilize a Mott insulator of photons against losses. Site- and time-resolved readout of the lattice allows us to investigate the microscopic details of the thermalization process through the dynamics of defect propagation and removal in the Mott phase. Our experiments demonstrate the power of superconducting circuits for studying strongly correlated matter in both coherent and engineered dissipative settings. In conjunction with recently demonstrated superconducting microwave Chern insulators, we expect that our approach will enable the exploration of topologically ordered phases of matter.

  View details for DOI 10.1038/s41586-019-0897-9

  View details for Web of Science ID 000457981800038

  View details for PubMedID 30728523

• Experimental data from a quantum computer verifies the generalized Pauli exclusion principle COMMUNICATIONS PHYSICS Smart, S. E., Schuster, D., Mazziotti, D. A. 2019; 2

  View details for DOI 10.1038/s42005-019-0110-3

  View details for Web of Science ID 000463774700001

• Probing the Berry curvature and Fermi arcs of a Weyl circuit PHYSICAL REVIEW B Lu, Y., Jia, N., Su, L., Owens, C., Juzeliunas, G., Schuster, D., Simon, J. 2019; 99 (2)

  View details for DOI 10.1103/PhysRevB.99.020302

  View details for Web of Science ID 000455053300001

• Optimized Compilation of Aggregated Instructions for Realistic Quantum Computers Shi, Y., Leung, N., Gokhale, P., Rossi, Z., Schuster, D., Hoffmann, H., Chong, F. T., ACM ASSOC COMPUTING MACHINERY. 2019: 1031-1044

  View details for DOI 10.1145/3297858.3304018

  View details for Web of Science ID 000584356000072

• Partial Compilation of Variational Algorithms for Noisy Intermediate-Scale Quantum Machines Gokhale, P., Ding, Y., Propson, T., Winkler, C., Leung, N., Shi, Y., Schuster, D., Hoffmann, H., Chong, F. T., Assoc Comp Machinery ASSOC COMPUTING MACHINERY. 2019: 266-278

  View details for DOI 10.1145/3352460.3358313

  View details for Web of Science ID 000519057400020

• Quantum control of surface acoustic-wave phonons NATURE Satzinger, K. J., Zhong, Y. P., Chang, H., Peairs, G. A., Bienfait, A., Chou, M., Cleland, A. Y., Conner, C. R., Dumur, E., Grebel, J., Gutierrez, I., November, B. H., Povey, R. G., Whiteley, S. J., Awschalom, D. D., Schuster, D. I., Cleland, A. N. 2018; 563 (7733): 661-665

  Abstract

  One of the hallmarks of quantum physics is the generation of non-classical quantum states and superpositions, which has been demonstrated in several quantum systems, including ions, solid-state qubits and photons. However, only indirect demonstrations of non-classical states have been achieved in mechanical systems, despite the scientific appeal and technical utility of such a capability1,2, including in quantum sensing, computation and communication applications. This is due in part to the highly linear response of most mechanical systems, which makes quantum operations difficult, as well as their characteristically low frequencies, which hinder access to the quantum ground state3-7. Here we demonstrate full quantum control of the mechanical state of a macroscale mechanical resonator. We strongly couple a surface acoustic-wave8 resonator to a superconducting qubit, using the qubit to control and measure quantum states in the mechanical resonator. We generate a non-classical superposition of the zero- and one-phonon Fock states and map this and other states using Wigner tomography9-14. Such precise, programmable quantum control is essential to a range of applications of surface acoustic waves in the quantum limit, including the coupling of disparate quantum systems15,16.

  View details for DOI 10.1038/s41586-018-0719-5

  View details for Web of Science ID 000451599900049

  View details for PubMedID 30464339

• Atomic layer deposition of titanium nitride for quantum circuits APPLIED PHYSICS LETTERS Shearrow, A., Koolstra, G., Whiteley, S. J., Earnest, N., Barry, P. S., Heremans, F., Awschalom, D. D., Shirokoff, E., Schuster, D. I. 2018; 113 (21)

  View details for DOI 10.1063/1.5053461

  View details for Web of Science ID 000450896600017

• Input-output theory for superconducting and photonic circuits that contain weak retroreflections and other weak pseudocavities PHYSICAL REVIEW A Cook, R., Schuster, D., Cleland, A. N., Jacobs, K. 2018; 98 (1)

  View details for DOI 10.1103/PhysRevA.98.013801

  View details for Web of Science ID 000436935800013

• Coupling an Ensemble of Electrons on Superfluid Helium to a Superconducting Circuit PHYSICAL REVIEW X Yang, G., Fragner, A., Koolstra, G., Ocola, L., Czaplewski, D. A., Schoelkopf, R. J., Schuster, D. I. 2016; 6 (1)

  View details for DOI 10.1103/PhysRevX.6.011031

  View details for Web of Science ID 000372726100001