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 ( P T ) 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- P T symmetric operations. We show that the QFI can be obviously enhanced by means of the P T symmetric operation in different regimes. In addition, we also show that the magnitude of the decoherence involved in the P T symmetric operation can be a general complex number, which extends the applicable scope of the P T symmetric operation approach.