Two-axis-twisting spin squeezing by multi-pass quantum erasure

TL;DR

This paper introduces a multi-pass quantum erasure technique to generate Heisenberg-limited spin squeezing in atomic ensembles, significantly improving entanglement quality for quantum metrology.

Contribution

It presents an all-optical interference-based method to erase unwanted atom-light entanglement, enabling high-degree spin squeezing with simple setups.

Findings

Achieves over 10 dB improvement in spin squeezing

Allows implementation with moderate experimental conditions

Enables efficient creation of many-body entangled states

Abstract

Many-body entangled states are key elements in quantum information science and quantum metrology. One important problem in establishing a high degree of many-body entanglement using optical techniques is the leakage of the system information via the light that creates such entanglement. We propose an all-optical interference-based approach to erase this information. Unwanted atom-light entanglement can be removed by destructive interference of three or more successive atom-light interactions, with only the desired effective atom-atom interaction left. This quantum erasure protocol allows implementation of Heisenberg-limited spin squeezing using coherent light and a cold or warm atomic ensemble. Calculations show that significant improvement in the squeezing exceeding 10 dB is obtained compared to previous methods, and substantial spin squeezing is attainable even under moderate experimental conditions. Our method enables the efficient creation of many-body entangled states with simple setups, and thus is promising for advancing technologies in quantum metrology and quantum information processing.