High-contrast dispersive readout of a superconducting flux qubit using a nonlinear resonator.
We demonstrate high-contrast state detection of a superconducting flux qubit. Detection is realized by probing the microwave transmission of a nonlinear resonator, based on a SQUID. Depending on the driving strength of the resonator, the detector can be operated in the monostable or the bistable mode. The bistable operation combines high-sensitivity with intrinsic latching. The measured contrast of Rabi oscillations is as high as 87%; of the missing 13%, only 3% of the loss of contrast is unaccounted for. Experiments involving two consecutive detection pulses are consistent with preparation of the qubit state by the first measurement.
Lupaşcu
A
A
Kavli Institute of Nanoscience, Delft University of Technology, Post Office Box 5046, 2600GA Delft, The Netherlands.
Driessen
E F C
EF
Roschier
L
L
Harmans
C J P M
CJ
Mooij
J E
JE