Spin squeezing: transforming one-axis-twisting into two-axis-twisting

TL;DR

This paper proposes a scheme to convert one-axis-twisting spin squeezing into two-axis-twisting, achieving Heisenberg-limited noise reduction and significantly improving quantum measurement precision.

Contribution

The authors introduce a method using repeated Rabi pulses to transform OAT into TAT spin squeezing, surpassing previous noise reduction limits.

Findings

Achieved Heisenberg-limited noise reduction of 1/N

Demonstrated a 10-fold improvement over OAT squeezing

Proposed a practical scheme for enhanced quantum metrology

Abstract

Squeezed spin states possess unique quantum correlation or entanglement that are of significant promises for advancing quantum information processing and quantum metrology. In recent back to back publications [C. Gross \textit{et al, Nature} \textbf{464}, 1165 (2010) and Max F. Riedel \textit{et al, Nature} \textbf{464}, 1170 (2010)], reduced spin fluctuations are observed leading to spin squeezing at -8.2dB and -2.5dB respectively in two-component atomic condensates exhibiting one-axis-twisting interactions (OAT). The noise reduction limit for the OAT interaction scales as $\propto 1/{N^{2/3}}$, which for a condensate with $N\sim 10^3$ atoms, is about 100 times below standard quantum limit. We present a scheme using repeated Rabi pulses capable of transforming the OAT spin squeezing into the two-axis-twisting type, leading to Heisenberg limited noise reduction $\propto 1/N$, or an extra 10-fold improvement for $N\sim 10^3$.