1202.5541 (J. E. Johnson et al.)

Heralded state preparation in a superconducting qubit    [PDF]

J. E. Johnson, C. Macklin, D. H. Slichter, R. Vijay, E. B. Weingarten, John Clarke, I. Siddiqi

We demonstrate high-fidelity, quantum non-demolition, single shot readout of
a superconducting flux qubit in which the pointer state histograms 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. Heralding also
enables a simple, fast qubit reset protocol without changing the system
parameters to induce Purcell relaxation.

View original: http://arxiv.org/abs/1202.5541