Improving Metrological Limit via Weak Measurement and Quantum Measurement Reversal

Abstract

Quantum parameter estimation is of fundamental importance in physics. Quantum resources, involving for instance entangled probes, offer a significant improvement in estimation precision over classical strategies for closed quantum systems. However, when noises such as decoherence are taken into account, the quantum gain may be jeopardized. In this paper, we show how the amplitude-damping decoherence degrades the estimation precision from the Heisenberg limit to the standard limit with the initial Greenberger-Horne-Zeilinger (GHZ) state being employed and demonstrate that the method of weak measurement and quantum measurement reversal can recover this estimation precision to the Heisenberg limit, even though at the price of a very low success probability.