Observation of Quasiparticle Pair Production and Quantum Entanglement in Atomic Quantum Gases Quenched to an Attractive Interaction

Cheng-An Chen, Sergei Khlebnikov, and Chen-Lung Hung
Phys. Rev. Lett. 127, 060404 – Published 6 August 2021
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Abstract

We report observations of quasiparticle pair production by a modulational instability in an atomic superfluid and present a measurement technique that enables direct characterization of quasiparticle quantum entanglement. 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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  • Received 23 February 2021
  • Accepted 8 July 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.060404

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & OpticalCondensed Matter, Materials & Applied PhysicsGeneral Physics

Authors & Affiliations

Cheng-An Chen1, Sergei Khlebnikov1,2, and Chen-Lung Hung1,2,*

  • 1Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
  • 2Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, Indiana 47907, USA

  • *clhung@purdue.edu

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Issue

Vol. 127, Iss. 6 — 6 August 2021

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