Determination of scale-invariant equations of state without fitting parameters: application to the two-dimensional Bose gas across the Berezinskii-Kosterlitz-Thouless transition

We present a general "fit-free" method for measuring the equation of state (EoS) of a scale-invariant gas. This method, which is inspired from the procedure introduced by Ku et al. [Science 335, 563 (2012)] for the unitary three-dimensional Fermi gas, provides a general formalism which can...

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Bibliographic Details
Published in:Physical review letters 2014-07, Vol.113 (2), p.020404-020404, Article 020404
Main Authors: Desbuquois, Rémi, Yefsah, Tarik, Chomaz, Lauriane, Weitenberg, Christof, Corman, Laura, Nascimbène, Sylvain, Dalibard, Jean
Format: Article
Language:English
Subjects:
Approximation
Benchmarking
Density
Equations of state
Formalism
Mathematical analysis
Three dimensional
Two dimensional
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Summary:We present a general "fit-free" method for measuring the equation of state (EoS) of a scale-invariant gas. This method, which is inspired from the procedure introduced by Ku et al. [Science 335, 563 (2012)] for the unitary three-dimensional Fermi gas, provides a general formalism which can be readily applied to any quantum gas in a known trapping potential, in the frame of the local density approximation. We implement this method on a weakly interacting two-dimensional Bose gas across the Berezinskii-Kosterlitz-Thouless transition and determine its EoS with unprecedented accuracy in the critical region. Our measurements provide an important experimental benchmark for classical-field approaches which are believed to accurately describe quantum systems in the weakly interacting but nonperturbative regime.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.113.020404