J. E. Johnson

Heralded state preparation in a superconducting qubit

  1. J. E. Johnson,
  2. C. Macklin,
  3. D. H. Slichter,
  4. R. Vijay,
  5. E. B. Weingarten,
  6. John Clarke,
  7. and I. Siddiqi
We demonstrate high-fidelity, quantum nondemolition, single-shot readout of a superconducting flux qubit in which the pointer state distributions can be resolved to below one part in
1000. In the weak excitation regime, continuous measurement permits the use of heralding to ensure initialization to a fiducial state, such as the ground state. This procedure boosts readout fidelity to 93.9% by suppressing errors due to spurious thermal population. Furthermore, heralding potentially enables a simple, fast qubit reset protocol without changing the system parameters to induce Purcell relaxation.
arxiv pdf