Giant Artificial Atoms and Waveguide QED

ORAL  · Invited

Abstract

In this talk, we present a demonstration of "giant artificial atoms" realized with superconducting qubits in a waveguide QED architecture. The superconducting qubits couple to the waveguide at multiple, well-separated locations. In this configuration, the dipole approximation no longer holds, and the giant atom may quantum mechanically self-interfere. This system enables tunable qubit-waveguide couplings with large on-off ratios and a coupling spectrum that can be engineered by design. Multiple, interleaved qubits in this architecture can be switched between protected and emissive configurations, while retaining qubit-qubit interactions mediated by the waveguide. Using this architecture, we generate a Bell state with 94% fidelity, despite both qubits being strongly coupled to the waveguide. We furthermore demonstrate directional emission with an artificial molecule with 97% fidelity. Such waveguide QED technologies are applicable to quantum interconnects and support architectural modularity.

*AWS Center for Quantum Computing, U.S. Army Research Office Grant No. W911NF-18-1-0411, the DOE Office of Science National Quantum Information Science Research Centers, Co-design Center for Quantum Advantage (C2QA) under Contract No. DE-SC0012704, and the Department of Defense under Air Force Contract No. FA8702-15-D-0001.

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Publication: On-demand directional photon emission using waveguide quantum electrodynamics
B. Kannan, A. Almanakly, Y. Sung, A. Di Paolo, D. A. Rower, J. Braumüller, A. Melville, B. M. Niedzielski, A. Karamlou, K. Serniak, A. Vepsäläinen, M. E. Schwartz, J. L. Yoder, R. Winik, J. I-Jan Wang, T. P. Orlando, S. Gustavsson, J. A. Grover, W. D. Oliver
arXiv:2203.01430 (2022), accepted to Nature Physics.

Generating spatially entangled itinerant photons with waveguide quantum electrodynamics
B. Kannan, D.L. Campbell, F. Vasconcelos, R. Winik, D.K. Kim, M. Kjaergaard, P. Krantz, A. Melville, B.M. Niedzielski, J.L. Yoder, T.P. Orlando, S. Gustavsson, W.D. Oliver
Science Advances Vol. 6, no. 41, eabb8780 (2020) | arXiv:2003.07300 (2020)

Waveguide quantum electrodynamics with giant superconducting artificial atoms
B. Kannan, M. Ruckriegel, D. Campbell, A.F. Kockum, J. Braumüller, D. Kim, M. Kjaergaard, P. Krantz, A. Melville, B.M. Niedzielski, A. Vepsäläinen, R. Winik, J. Yoder, F. Nori, T.P. Orlando, S. Gustavsson, W.D. Oliver
Nature 583, 775–779 (2020) | arXiv:1912.12233 (2019)

Presenters

  • William D Oliver

    • Massachusetts Institute of Technology MIT
    • Massachusetts Institute of Technology (MIT), MIT Lincoln Laboratory
    • Massachusetts Institute of Technology (MIT)
    • Massachusetts Institute of Technology
    • Massachusetts Institute of Technology, MIT Lincoln Laboratory

Authors

  • William D Oliver

    • Massachusetts Institute of Technology MIT
    • Massachusetts Institute of Technology (MIT), MIT Lincoln Laboratory
    • Massachusetts Institute of Technology (MIT)
    • Massachusetts Institute of Technology
    • Massachusetts Institute of Technology, MIT Lincoln Laboratory