Reversing the weak quantum measurement for a photonic qubit

Yong Su Kim, Young Wook Cho, Young Sik Ra, Yoon Ho Kim

Research output: Contribution to journalArticlepeer-review

171 Citations (Scopus)


We demonstrate the conditional reversal of a weak (partialcollapse) quantum measurement on a photonic qubit. The weak quantum measurement causes a nonunitary transformation of a qubit which is subsequently reversed to the original state after a successful reversing operation. Both the weak measurement and the reversal operation are implemented linear optically. The state recovery fidelity, determined by quantum process tomography, is shown to be over 94% for partial-collapse strength up to 0.9. We also experimentally study information gain due to the weak measurement and discuss the role of the reversing operation as an information erasure.

Original languageEnglish
Pages (from-to)11978-11985
Number of pages8
JournalOptics Express
Issue number14
Publication statusPublished - 2009 Jul 6

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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