Quantum thermometry based on interferometric power

Abstract

In the field of quantum thermometry, usually temperature is estimated by the framework of quantum metrology. In this work, an alternative approach to quantum thermometry is suggested, based on interferometric power (IP). IP is defined as the worst-case quantum Fisher information in a double-channel interferometer. Specifically, the time evolution of the IP for a two-qubit state as a probe contacting with a finite-temperature bath is considered. The IP dynamics of the probe with three kinds of initial states (i.e., entangled, separable, and mixed) strongly depend on the bath temperature. The dynamical evolution of IP would be measured experimentally, considering that the IP is a measurable quantity in the experiment. Thus, the IP dynamics can be adopted to extract the value of the bath temperature directly. In this sense, the IP could be exploited as a quantum thermometer.