Uncollapsing of a quantum state in a superconducting phase qubit

Date
Authors
Katz, Nadav
Neeley, Matthew
Ansmann, M.
Bialczak, Radoslaw C.
Hofheinz, M.
Lucero, Erik
O'Connell, A.
Wang, H.
Cleland, A. N.
Martinis, John M.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Description
We demonstrate in a superconducting qubit the conditional recovery ("uncollapsing") of a quantum state after a partial-collapse measurement. A weak measurement extracts information and results in a non-unitary transformation of the qubit state. However, by adding a rotation and a second partial measurement with the same strength, we erase the extracted information, effectively canceling the effect of both measurements. The fidelity of the state recovery is measured using quantum process tomography and found to be above 70% for partial-collapse strength less than 0.6.
Comment: 4 pages, 4 figures
Keywords
Quantum Physics, Condensed Matter - Superconductivity
Citation
Collections