Academic Appointments

2023-24 Courses

Stanford Advisees

All Publications

  • 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)
  • 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


    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)
  • 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)
  • 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


    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)
  • 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)
  • 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


    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

  • 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
  • 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


    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