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


Abstract in English

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 $Nsim 10^3$ 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 $Nsim 10^3$.

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