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Tan's two-body contact across the superfluid transition of a planar Bose gas.

ABSTRACT: Tan's contact is a quantity that unifies many different properties of a low-temperature gas with short-range interactions, from its momentum distribution to its spatial two-body correlation function. Here, we use a Ramsey interferometric method to realize experimentally the thermodynamic definition of the two-body contact, i.e., the change of the internal energy in a small modification of the scattering length. Our measurements are performed on a uniform two-dimensional Bose gas of ⁸⁷Rb atoms across the Berezinskii-Kosterlitz-Thouless superfluid transition. They connect well to the theoretical predictions in the limiting cases of a strongly degenerate fluid and of a normal gas. They also provide the variation of this key quantity in the critical region, where further theoretical efforts are needed to account for our findings.

SUBMITTER: Zou YQ

PROVIDER: S-EPMC7858573 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Tan's two-body contact across the superfluid transition of a planar Bose gas.

Zou Y-Q YQ Bakkali-Hassani B B Maury C C Le Cerf É É Nascimbene S S Dalibard J J Beugnon J J

Nature communications 20210203 1

Tan's contact is a quantity that unifies many different properties of a low-temperature gas with short-range interactions, from its momentum distribution to its spatial two-body correlation function. Here, we use a Ramsey interferometric method to realize experimentally the thermodynamic definition of the two-body contact, i.e., the change of the internal energy in a small modification of the scattering length. Our measurements are performed on a uniform two-dimensional Bose gas of <sup>87</sup> ...[more]

PMID: 33536418

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