Criticality of environmental information obtainable by dynamically controlled quantum probes

TL;DR

This paper uncovers a phase transition in the information obtainable by a quantum probe about environmental fluctuations, highlighting the importance of dynamical control for optimal environmental estimation.

Contribution

It introduces a universal approach combining decoherence control and quantum estimation theory to reveal critical behavior in environmental information extraction.

Findings

Critical behavior akin to a phase transition in quantum environmental information

Dynamical control enables a sharp transition between short and long environmental memory phases

Facilitates optimal estimation of environmental memory time

Abstract

A universal approach to decoherence control combined with quantum estimation theory reveals a critical behavior, akin to a phase transition, of the information obtainable by a qubit probe concerning the memory time of environmental fluctuations. This criticality emerges only when the probe is subject to dynamical control. It gives rise to a sharp transition between two dynamical phases characterized by either a short or long memory time compared to the probing time. This phase-transition of the environmental information is a fundamental feature that facilitates the attainment of the highest estimation precision of the environment memory-time and the characterization of probe dynamics.