Probing cosmic string spacetime through parameter estimation

TL;DR

This paper applies quantum metrology techniques to estimate the deficit angle of cosmic string spacetime using a two-level atom probe, analyzing how various parameters influence the precision of this estimation.

Contribution

It introduces a quantum metrology approach to relativistic spacetime parameter estimation, specifically optimizing the quantum Fisher information for cosmic string spacetime.

Findings

Quantum Fisher information depends on deficit angle, evolution time, and probe parameters.

Optimal estimation strategies are identified by maximizing quantum Fisher information.

Different polarization cases yield varying behaviors and magnitudes of QFI.

Abstract

Quantum metrology studies the ultimate precision limit of physical quantities by using quantum strategy. In this paper we apply the quantum metrology technologies to the relativistic framework for estimating the deficit angle parameter of cosmic string spacetime. We use a two-level atom coupled to electromagnetic fields as the probe and derive its dynamical evolution by treating it as an open quantum system. We estimate the deficit angle parameter by calculating its quantum Fisher information(QFI). It is found that the quantum Fisher information depends on the deficit angle, evolution time, detector initial state, polarization direction, and its position. We then identify the optimal estimation strategies, i.e., maximize the quantum Fisher information via all the associated parameters, and therefore optimize the precision of estimation. Our results show that for different polarization cases the QFIs have different behaviors and different orders of magnitude, which may shed light on the exploration of cosmic string spacetime.