Manipulation of collective quantum states in Bose-Einstein condensates by continuous imaging

TL;DR

This paper presents a Gaussian state framework for understanding how continuous, nondestructive imaging and feedback influence quantum states in Bose-Einstein condensates, focusing on optimizing measurement back action effects like squeezing and entanglement.

Contribution

It introduces a Gaussian state approach to analyze the impact of finite spatial resolution on quantum state manipulation in BECs during continuous imaging.

Findings

Finite spatial resolution affects squeezing and entanglement.

Optimization of probe beam and detector geometry enhances quantum state control.

Measurement back action can be tailored for desired quantum correlations.

Abstract

We develop a Gaussian state treatment that allows a transparent quantum description of the continuous, nondestructive imaging of and feedback on a Bose-Einstein condensate. We have previously demonstrated [Phys. Rev. Lett. \textbf{115}, 060401 (2015)] that the measurement back action of stroboscopic imaging leads to selective squeezing and entanglement of quantized density oscillations. Here, we investigate how the squeezing and entanglement are affected by the finite spatial resolution and geometry of the probe laser beam and of the detector and how they can be optimized.