Coherent state evolution in a superconducting qubit from partial-collapse measurement.
Measurement is one of the fundamental building blocks of quantum-information processing systems. Partial measurement, where full wavefunction collapse is not the only outcome, provides a detailed test of the measurement process. We introduce quantum-state tomography in a superconducting qubit that exhibits high-fidelity single-shot measurement. For the two probabilistic outcomes of partial measurement, we find either a full collapse or a coherent yet nonunitary evolution of the state. This latter behavior explicitly confirms modern quantum-measurement theory and may prove important for error-correction algorithms in quantum computation.
Katz
N
N
Department of Physics and California NanoSystems Institute, University of California, Santa Barbara, CA 93106, USA.
Ansmann
M
M
Bialczak
Radoslaw C
RC
Lucero
Erik
E
McDermott
R
R
Neeley
Matthew
M
Steffen
Matthias
M
Weig
E M
EM
Cleland
A N
AN
Martinis
John M
JM
Korotkov
A N
AN