Improving parameter estimation precision by parity-time symmetric operation

Abstract

The enhancement of the precision of phase estimation in quantum metrology is investigated by employing parity-time () symmetric operation. We derive the exact expressions of the quantum Fisher information (QFI) and the success probability of the phase estimation for an exactly solving model consisting of a qubit interacting with a structured reservoir. Special attention is paid to the two schemes, i.e. pre-and post- symmetric operations. We show that the QFI can be obviously enhanced by means of the symmetric operation in different regimes. In addition, we also show that the magnitude of the decoherence involved in the symmetric operation can be a general complex number, which extends the applicable scope of the symmetric operation approach.