Linear quantum measurements

TL;DR

This paper develops a linear response framework for quantum measurements, providing a universal relation that characterizes detector efficiency and the trade-off between information gain and back-action dephasing.

Contribution

It introduces a generic quantitative relation for quantum detectors based on linear response theory, analogous to the fluctuation-dissipation theorem.

Findings

Derives a universal relation for quantum detector characteristics.

Quantifies the trade-off between measurement information and back-action.

Provides insights into detector efficiency in quantum measurements.

Abstract

Linear response theory describes quantum measurement with an arbitrary detector weakly coupled to a measured system. This description produces generic quantitative relation characterizing the detector that is analogous to the fluctuation-dissipation theorem for equilibrium systems. The detector characteristic obtained in this way shows how efficient the trade-off is between the back-action dephasing and information acquisition by the detector.