Quantum metrological capability as a probe for quantum phase transition

TL;DR

This paper introduces a quantum metrological method using a quench-interferometric approach to detect quantum phase transitions without requiring ground state cooling, by analyzing quantum Fisher information peaks near critical points.

Contribution

It presents a novel dynamical quench-interferometric framework that links quantum metrology with phase transition detection in many-body systems.

Findings

Quantum Fisher information peaks near critical points.

QPT boundary can be identified via quantum fluctuations.

Method works without ground state cooling.

Abstract

The comprehension of quantum phase transitions (QPTs) is considered as a critical foothold in the field of many-body physics. Developing protocols to effectively identify and understand QPTs thus represents a key but challenging task for present quantum simulation experiments. Here, we establish a dynamical quench-interferometric framework to probe a zero-temperature QPT, which utilizes the evolved state by quenching the QPT Hamiltonian as input of a unitary interferometer. The metrological capability quantified by the quantum Fisher information captivatingly shows an unique peak in the vicinity of the quantum critical point, allowing us to probe the QPT without cooling the system to its ground state. We show that the probing can be implemented by extracting quantum fluctuations of the interferometric generator as well as parameter estimation uncertainty of the interferometric phase, and subsequently allows identifying the boundary of the phase diagram. Our results establish an important link between QPTs and quantum metrology, and enrich the toolbox of studying non-equilibrium many-body physics in current quantum simulators.