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Experimental realization of the soft 0-π qubit

Invited

Abstract

Encoding a qubit in logical quantum states with wavefunctions characterized by disjoint support and robust energies can offer simultaneous protection against relaxation and pure dephasing. One of the most promising candidates for such a fully-protected superconducting qubit is the 0-π circuit [Brooks et al., Phys. Rev. A 87, 052306 (2013)]. Here, we realize the proposed circuit topology in an experimentally obtainable parameter regime and show that the device, which we call as the soft 0-π qubit, hosts logical states with disjoint support that are exponentially (first-order) protected against charge (flux) noise. Multi-tone spectroscopy measurements reveal the energy-level structure of the system, which can be precisely described by a simple two-mode Hamiltonian. Using a Raman-type protocol, we exploit a higher-lying charge-insensitive energy level of the device to realize coherent population transfer and logical operations. The measured relaxation (T1 = 1.6 ms) and dephasing (TR = 9 μs, T2E = 25 µs) times demonstrate that the soft 0-π circuit not only broadens the family of superconducting qubits, but also constitutes an important step towards quantum computing with intrinsically protected superconducting qubits.

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Presenters

  • Andras Gyenis

    Princeton University, Department of Electrical Engineering, Princeton University

Authors

  • Andras Gyenis

    Princeton University, Department of Electrical Engineering, Princeton University

  • Pranav Mundada

    Princeton University, Q-CTRL, Department of Electrical Engineering, Princeton University

  • Agustin Di Paolo

    Physics, Universite de Sherbrooke, Universite de Sherbrooke, Département de Physique, Université de Sherbrooke, Institut quantique & Departement de Physique, Universite de Sherbrooke

  • Thomas Hazard

    MIT Lincoln Laboratory, MIT Lincoln Lab, Department of Electrical Engineering, Princeton University, Lincoln Laboratory, MIT, MIT - Lincoln Laboratory

  • Xinyuan You

    Northwestern University, Department of Physics and Astronomy, Northwestern University, Physics, Northwestern University

  • David I Schuster

    University of Chicago, The James Franck Institute and Department of Physics, University of Chicago, The James Franck Institute and Department of Physics, The University of Chicago

  • Jens Koch

    Physics, Northwestern University, Northwestern University, Department of Physics and Astronomy, Northwestern University, Physics and Astronomy, Northwestern University

  • Alexandre Blais

    Universite de Sherbrooke, Institut Quantique and Département de Physique, Université de Sherbrooke, Physics, Universite de Sherbrooke, Université de Sherbrook, Université de Sherbrooke, Département de Physique, Université de Sherbrooke, Institut quantique & Departement de Physique, Universite de Sherbrooke, Institut quantique and Departement de physique, Universite de Sherbrooke, Institut Quantique and Department de Physique, Universite de Sherbrooke, Institut quantique and Departement de Physique, Universite de Sherbrooke

  • Andrew Houck

    Princeton University, Department of Electrical Engineering, Princeton University