A two-dimensional Bose fluid is a remarkably rich many-body system, which allows one to revisit several features of quantum statistical physics. Firstly, the role of thermal fluctuations is enhanced compared to the 3D case, which destroys the ordered state associated with Bose–Einstein condensation. However interactions between particles can still cause a super¿uid transition, thanks to the Berezinskii–Kosterlitz–Thouless mechanism. Secondly, the weakly interacting Bose gas in 2D must be scale-invariant, a remarkable feature that manifests itself in the very simple form taken by the equation of state of the fluid. Thirdly it can give rise to special kind of excitations, not bosonic, nor fermionic in the presence of orbital magnetism.
In this talk I will first present some recent experimental progress in the investigation of 2d bosonic atomic gases, with the observation of superfluid behavior and the measurement of the scale-invariant equation of state. I will then describe a promising scheme based on optical flux lattices, which should allow one to achieve quantum-Hall type states in a 2D Bose gas with realistic parameters.
T. Yefsah, R. Desbuquois, L. Chomaz, K. J. Günter, J. Dalibard, Phys. Rev. Lett. 107, 130401 (2011): Exploring the thermodynamics of a two-dimensional Bose gas
R. Desbuquois, L. Chomaz, T. Yefsah, J. Léonard, J. Beugnon, C. Weitenberg, J. Dalibard, Nature Physics 8, 645 (2012): Superfluid behaviour of a two-dimensional Bose gas
N. R. Cooper, J. Dalibard, arXiv:1212.3552, to appear in Phys. Rev. Lett.:
Reaching Fractional Quantum Hall States with Optical Flux Lattices