An optical lattice with sound
Date
11/11/2021Author
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Abstract
Quantized sound waves—phonons—govern the elastic response of crystalline materials, and also play an integral part in determining their thermodynamic properties and electrical response (for example, by binding electrons into superconducting Cooper pairs). The physics of lattice phonons and elasticity is absent in simulators of quantum solids constructed of neutral atoms in periodic light potentials: unlike real solids, traditional optical lattices are silent because they are infinitely stiff. Optical-lattice realizations of crystals therefore lack some of the central dynamical degrees of freedom that determine the low-temperature properties of real materials. Here, we create an optical lattice with phonon modes using a Bose–Einstein condensate (BEC) coupled to a confocal optical resonator. Playing the role of an active quantum gas microscope, the multimode cavity QED system both images the phonons and induces the crystallization that supports phonons via short-range, photon-mediated atom–atom interactions. Dynamical susceptibility measurements reveal the phonon dispersion relation, showing that these collective excitations exhibit a sound speed dependent on the BEC–photon coupling strength. Our results pave the way for exploring the rich physics of elasticity in quantum solids, ranging from quantum melting transitions to exotic ‘fractonic’ topological defects in the quantum regime.
Citation
Guo , Y , Kroeze , R M , Marsh , B P , Gopalakrishnan , S , Keeling , J & Lev , B L 2021 , ' An optical lattice with sound ' , Nature , vol. 599 , no. 7884 , pp. 211-215 . https://doi.org/10.1038/s41586-021-03945-x
Publication
Nature
Status
Peer reviewed
ISSN
0028-0836Type
Journal article
Rights
Copyright © 2021 The Author(s), under exclusive licence to Springer Nature Limited. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1038/s41586-021-03945-x.
Description
Funding: We acknowledge funding support from the Army Research Office. Y.G. and B.M. acknowledge funding from the Stanford Q-FARM Graduate Student Fellowship and the NSF Graduate Research Fellowship, respectively. S.G. acknowledges support from NSF Grant No. DMR-1653271.Collections
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