Non-destructive optical measurement of relative phase between two Bose condensates

TL;DR

This paper demonstrates a non-destructive optical method to measure the relative phase between two Bose condensates by analyzing scattered photons, revealing quantum interference effects and potential state distinctions.

Contribution

It introduces a novel non-destructive measurement technique using light scattering to determine the relative phase of Bose condensates, even from initial number states.

Findings

Photon detection rate depends on the condensates' relative phase.

Measurement process is non-destructive, leaving atom numbers unchanged.

Method can distinguish initial quantum states of condensates.

Abstract

We study the interaction of light with two Bose condensates as an open quantum system. The two overlapping condensates occupy two different Zeeman sublevels and two driving light beams induce a coherent quantum tunneling between the condensates. We derive the master equation for the system. It is shown that stochastic simulations of the measurements of spontaneously scattered photons establish the relative phase between two Bose condensates, even though the condensates are initially in pure number states. These measurements are non-destructive for the condensates, because only light is scattered, but no atoms are removed from the system. Due to the macroscopic quantum interference the detection rate of photons depends substantially on the relative phase between the condensates. This may provide a way to distinguish, whether the condensates are initially in number states or in coherent states.