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arXiv · 2102.11215

Observation of quasiparticle pair-production and quantum entanglement in atomic quantum gases quenched to an attractive interaction

Cheng-An Chen·Sergei Khlebnikov·Chen-Lung Hung
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Abstract

We report observation of quasiparticle pair-production and characterize quantum entanglement created by a modulational instability in an atomic superfluid. By quenching the atomic interaction to attractive and then back to weakly repulsive, we produce correlated quasiparticles and monitor their evolution in a superfluid through evaluating the in situ density noise power spectrum, which essentially measures a 'homodyne' interference between ground state atoms and quasiparticles of opposite momenta. We observe large amplitude growth in the power spectrum and subsequent coherent oscillations in a wide spatial frequency band within our resolution limit, demonstrating coherent quasiparticle generation and evolution. The spectrum is observed to oscillate below a quantum limit set by the Peres-Horodecki separability criterion of continuous-variable states, thereby confirming quantum entanglement between interaction quench-induced quasiparticles.

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Cheng-An Chen, Sergei Khlebnikov, Chen-Lung Hung. 2021-02-22. Observation of quasiparticle pair-production and quantum entanglement in atomic quantum gases quenched to an attractive interaction. https://doi.org/10.1103/physrevlett.127.060404

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