Faraday imaging induced squeezing of a double-well Bose-Einstein condensate

TL;DR

This paper investigates how non-destructive Faraday imaging can generate and sustain spin squeezing in a double-well Bose-Einstein condensate, even amid tunneling and noise, using an exact wavefunction approach.

Contribution

It introduces an exact wavefunction method to analyze spin squeezing in a double-well BEC under Faraday imaging, accounting for dephasing and tunneling effects.

Findings

Monitoring at zero detection current minimizes measurement backaction.

Spin squeezing is achieved along the coupled axis in the weak interaction regime.

Squeezing persists despite tunneling and dephasing noise.

Abstract

We examine how non-destructive measurements generate spin squeezing in an atomic Bose-Einstein condensate confined in a double-well trap. The condensate in each well is monitored using coherent light beams in a Mach-Zehnder configuration that interacts with the atoms through a quantum nondemolition Hamiltonian. We solve the dynamics of the light-atom system using an exact wavefunction approach, in the presence of dephasing noise, which allows us to examine arbitrary interaction times and a general initial state. We find that monitoring the condensate at zero detection current and with identical coherent light beams minimizes the backaction of the measurement on the atoms. In the weak atom-light interaction regime, we find the mean spin direction is relatively unaffected, while the variance of the spins is squeezed along the axis coupled to the light. Additionally, squeezing persists in the presence of tunneling and dephasing noise.