Acoustic analog to the dynamical Casimir effect in a Bose-Einstein condensate.
We have modulated the density of a trapped Bose-Einstein condensate by changing the trap stiffness, thereby modulating the speed of sound. We observe the creation of correlated excitations with equal and opposite momenta, and show that for a well-defined modulation frequency, the frequency of the excitations is half that of the trap modulation frequency.
Laboratoire Charles Fabry, Institut d'Optique, CNRS, Université Paris-Sud, 2 avenue Augustin Fresnel, 91127 Palaiseau, France.
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JC
Jaskula
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Partridge
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M
Bonneau
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Lopes
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Ruaudel
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Boiron
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Westbrook