Correlation functions and conditioned quantum dynamics in photodetection theory

TL;DR

This paper presents a new approach to calculating correlations in photodetection signals from quantum light sources using conditioned quantum dynamics, providing deeper insights and interpretations beyond traditional methods.

Contribution

It introduces a framework based on conditioned quantum dynamics and past quantum states to analyze photodetection correlations, extending traditional master equation approaches.

Findings

Conditioned dynamics offer alternative calculations for photodetection correlations.

Transient correlations between field measurements and photon counts are explained.

Past quantum states theory accounts for correlations in monitored quantum systems.

Abstract

Correlations in photodetection signals from quantum light sources are conventionally calculated by application of the source master equation and the quantum regression theorem. In this article we show how the conditioned dynamics, associated with the quantum theory of measurements, allows calculations and offers interpretations of the behaviour of the same quantities. Our theory is illustrated for photon counting and field-amplitude measurements, and we show, in particular, how transient correlations between field-amplitude measurements and later photon counting events can be accounted for by a recently developed theory of past quantum states of a monitored quantum system.