Superfluid behaviour of a two-dimensional Bose gas

article Superfluid behaviour of a two-dimensional Bose gas published yes Rémi Desbuquois author Lauriane Chomaz author Tarik Yefsah author Julian Leonard author b75b3f45-7995-11ef-9bfd-9a9cd02c3577 Jérôme Beugnon author Christof Weitenberg author Jean Dalibard author Owing to thermal fluctuations, two-dimensional (2D) systems cannot undergo a conventional phase transition associated with the breaking of a continuous symmetry1. Nevertheless they may exhibit a phase transition to a state with quasi-long-range order via the Berezinskii–Kosterlitz–Thouless (BKT) mechanism2. A paradigm example is the 2D Bose fluid, such as a liquid helium film3, which cannot condense at non-zero temperature although it becomes superfluid above a critical phase space density. The quasi-long-range coherence and the microscopic nature of the BKT transition were recently explored with ultracold atomic gases4,5,6. However, a direct observation of superfluidity in terms of frictionless flow is still missing for these systems. Here we probe the superfluidity of a 2D trapped Bose gas using a moving obstacle formed by a micrometre-sized laser beam. We find a dramatic variation of the response of the fluid, depending on its degree of degeneracy at the obstacle location. Springer Nature2012 eng Nature Physics 1745-2473 1745-2481 1205.453610.1038/nphys2378 89645-648 yes R. Desbuquois, L. Chomaz, T. Yefsah, J. Leonard, J. Beugnon, C. Weitenberg, J. Dalibard, Nature Physics 8 (2012) 645–648. Desbuquois, Rémi, et al. “Superfluid Behaviour of a Two-Dimensional Bose Gas.” Nature Physics, vol. 8, no. 9, Springer Nature, 2012, pp. 645–48, doi:<a href="https://doi.org/10.1038/nphys2378">10.1038/nphys2378</a>. Desbuquois, Rémi, Lauriane Chomaz, Tarik Yefsah, Julian Leonard, Jérôme Beugnon, Christof Weitenberg, and Jean Dalibard. “Superfluid Behaviour of a Two-Dimensional Bose Gas.” Nature Physics. Springer Nature, 2012. <a href="https://doi.org/10.1038/nphys2378">https://doi.org/10.1038/nphys2378</a>. Desbuquois, R., Chomaz, L., Yefsah, T., Leonard, J., Beugnon, J., Weitenberg, C., & Dalibard, J. (2012). Superfluid behaviour of a two-dimensional Bose gas. Nature Physics. Springer Nature. <a href="https://doi.org/10.1038/nphys2378">https://doi.org/10.1038/nphys2378</a> Desbuquois R, Chomaz L, Yefsah T, et al. Superfluid behaviour of a two-dimensional Bose gas. Nature Physics. 2012;8(9):645-648. doi:<a href="https://doi.org/10.1038/nphys2378">10.1038/nphys2378</a> Desbuquois R, Chomaz L, Yefsah T, Leonard J, Beugnon J, Weitenberg C, Dalibard J. 2012. Superfluid behaviour of a two-dimensional Bose gas. Nature Physics. 8(9), 645–648. R. Desbuquois et al., “Superfluid behaviour of a two-dimensional Bose gas,” Nature Physics, vol. 8, no. 9. Springer Nature, pp. 645–648, 2012. 182012024-10-07T11:50:19Z2024-10-07T12:05:22Z