Atomic beam correlations and the quantum state of the micromaser

TL;DR

This paper explores how correlation measurements of atoms passing through a micromaser reveal detailed properties of the quantum state of the cavity's radiation field, uncovering complex phase structures beyond traditional observables.

Contribution

It demonstrates that atomic correlation lengths relate to photon statistics and phase structures, verified through theoretical calculations and high-precision Monte-Carlo simulations.

Findings

Correlation length indicates super- or sub-Poissonian photon statistics.

Correlations can extend over many cavity decay times.

Correlation measurements reveal richer phase structures than single-time observables.

Abstract

Correlation measurements on the states of two-level atoms having passed through a micromaser at different times can be used to infer properties of the quantum state of the radiation field in the cavity. Long(short) correlation length in time is to some extent associated with super(sub)-Poissonian photon statistics. The correlation length is also an indicator of a phase structure much richer than what is revealed by the usual single-time observables, like the atomic inversion or the Mandel quality factor. In realistic experimental situations the correlations may extend over many times the decay time of the cavity. Our assertions are verified by comparing theoretical calculations with a high-precision Monte-Carlo simulation of the micromaser system.