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Published on: November 11, 2013
Reversing the weak quantum measurement for a photonic qubit
Yong-Su Kim1, Young-Wook Cho, Young-Sik Ra
1Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Korea. yskim25@postech.ac.kr
Abstract:
We demonstrate the conditional reversal of a weak (partial-collapse) 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.
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