Shot noise of interference between independent atomic systems

TL;DR

This paper analyzes shot noise in interference patterns of independent atomic systems, showing how noise depends on initial states and number of systems, with implications for distinguishing quantum states.

Contribution

It provides a detailed analysis of shot noise dependence on initial states and extends the understanding to multiple systems, applicable to both bosons and fermions.

Findings

Variance of interference amplitude decreases with particle number

Shot noise can distinguish different initial quantum states

Interference contrast variance vanishes as number of systems increases

Abstract

We study shot (counting) noise of the amplitude of interference between independent atomic systems. In particular, for the two interfering systems the variance of the fringe amplitude decreases as the inverse power of the number of particles per system with the coefficient being a non-universal number. This number depends on the details of the initial state of each system so that the shot noise measurements can be used to distinguish between such states. We explicitly evaluate this coefficient for the two cases of the interference between bosons in number states and in broken symmetry states. We generalize our analysis to the interference of multiple independent atomic systems. We show that the variance of the interference contrast vanishes as the inverse power of the number of the interfering systems. This result, implying high signal to noise ratio in the interference experiments, holds both for bosons and for fermions.