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arXiv · 1709.04531

Negative-mass instability of the spin and motion of an atomic gas driven by optical cavity backaction

Jonathan Kohler·Justin A. Gerber·Emma Dowd·Dan M. Stamper-Kurn
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Abstract

We realize a spin-orbit interaction between the collective spin precession and center-of-mass motion of a trapped ultracold atomic gas, mediated by spin- and position-dependent dispersive coupling to a driven optical cavity. The collective spin, precessing near its highest-energy state in an applied magnetic field, can be approximated as a negative-mass harmonic oscillator. When the Larmor precession and mechanical motion are nearly resonant, cavity mediated coupling leads to a negative-mass instability, driving exponential growth of a correlated mode of the hybrid system. We observe this growth imprinted on modulations of the cavity field and estimate the full covariance of the resulting two-mode state by observing its transient decay during subsequent free evolution.

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Jonathan Kohler, Justin A. Gerber, Emma Dowd, Dan M. Stamper-Kurn. 2018-01-02. Negative-mass instability of the spin and motion of an atomic gas driven by optical cavity backaction. https://doi.org/10.1103/physrevlett.120.013601

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