Reversal of the weak measurement of a quantum state in a superconducting phase qubit

Nadav Katz*, Matthew Neeley, M. Ansmann, Radoslaw C. Bialczak, M. Hofheinz, Erik Lucero, A. O'Connell, H. Wang, A. N. Cleland, John M. Martinis, Alexander N. Korotkov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

225 Scopus citations

Abstract

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 nonunitary transformation of the qubit state. However, by adding a rotation and a second partial measurement with the same strength, we erase the extracted information, 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.

Original languageAmerican English
Article number200401
JournalPhysical Review Letters
Volume101
Issue number20
DOIs
StatePublished - 10 Nov 2008

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