Bragg spectroscopic interferometer and quantum measurement-induced correlations in atomic Bose-Einstein condensates

TL;DR

This paper provides a theoretical analysis of a Bragg spectroscopic interferometer with atomic Bose-Einstein condensates, revealing how quantum measurement back-action influences phase creation and identifying regimes relevant for quantum-enhanced sensing.

Contribution

It introduces a theoretical framework explaining phase generation via measurement back-action and distinguishes two phase evolution regimes in BEC interferometry.

Findings

Quantum measurement back-action creates the phase in the interferometer.

Two regimes of phase evolution: running and trapped.

Potential for quantum-enhanced interferometric schemes.

Abstract

We theoretically analyze the Bragg spectroscopic interferometer of two spatially separated atomic Bose-Einstein condensates that was experimentally realized by Saba et al. [Science 2005 v307 p1945] by continuously monitoring the relative phase evolution. Even though the atoms in the light-stimulated Bragg scattering interact with intense coherent laser beams, we show that the phase is created by quantum measurement-induced back-action on the homodyne photo-current of the lasers, opening possibilities for quantum-enhanced interferometric schemes. We identify two regimes of phase evolution: a running phase regime which was observed in the experiment of Saba et al., that is sensitive to an energy offset and suitable for an interferometer, and a trapped phase regime, that can be insensitive to applied forces and detrimental to interferometric applications.