V. Milchakov

Fast high fidelity quantum non-demolition qubit readout via a non-perturbative cross-Kerr coupling

  1. R. Dassonneville,
  2. T. Ramos,
  3. V. Milchakov,
  4. L. Planat,
  5. É. Dumur,
  6. F. Foroughi,
  7. J. Puertas,
  8. S. Leger,
  9. K. Bharadwaj,
  10. J. Delaforce,
  11. K. Rafsanjani,
  12. C. Naud,
  13. W. Hasch-Guichard,
  14. J.J. García-Ripoll,
  15. N. Roch,
  16. and O. Buisson
Qubit readout is an indispensable element of any quantum information processor. In this work we propose an original coupling scheme between qubit and cavity mode based on a non-perturbative
cross-Kerr interaction. It leads to an alternative readout mechanism for superconducting qubits. This scheme, using the same experimental techniques as the perturbative cross-Kerr coupling (dispersive interaction), leads to an alternative readout mechanism for superconducting qubits. This new process, being non-perturbative, maximizes speed of qubit readout, single-shot fidelity and its quantum non-demolition (QND) behavior at the same time, while minimizing the effect of unwanted decay channels such as, for example, the Purcell effect. We observed 97.4 % single-shot readout fidelity for short 50 ns pulses. Using long measurement, we quantified the QND-ness to 99 %.
arxiv pdf