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arXiv · 1611.10135

Preserving coherent spin and squeezed spin states of a spin-1 Bose-Einstein condensate with rotary echoes

Jun Zhang·Yingying Han·Peng Xu·Wenxian Zhang
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Abstract

A challenge in precision measurement with squeezed spin state arises from the spin dephasing due to stray magnetic fields. To suppress such environmental noises, we employ a continuous driving protocol, rotary echo, to enhance the spin coherence of a spin-1 Bose-Einstein condensate in stray magnetic fields. Our analytical and numerical results show that the coherent and the squeezed spin states are preserved for a significantly long time, compared to the free induction decay time, if the condition $hτ= mπ$ is met with $h$ the pulse amplitude and $τ$ pulse width. In particular, both the spin average and the spin squeezing, including the direction and the amplitude, are simultaneously fixed for a squeezed spin state. Our results point out a practical way to implement quantum measurements based on a spin-1 condensate beyond the standard quantum limit.

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Jun Zhang, Yingying Han, Peng Xu, Wenxian Zhang. 2016-11-30. Preserving coherent spin and squeezed spin states of a spin-1 Bose-Einstein condensate with rotary echoes. https://doi.org/10.1103/physreva.94.053608

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