Multispecies bosonic gases
Experimental progresses in ultra-cold quantum gases has brought also some new quantum systems in which the correlation effects are very visible. Amonge these systems, there are mixtures of different types of gases. Bose-Bose mixtures are succesful examples. These mixtures are created e.g from Rb and K. The uniqe advantage of them is that all inter and intra species interactions are tunable therefore in principle it is possible to explore magnetic ordering due to the correlation effects.
The spin-ordering for Bosons is crucial to undrestand the quantum magnetism of Bosons. Previously this issue has been addressed in more analytical way which provided the phase diagram of the two-component Bose gas in an optical lattice [1]. To get more accurate results on a full range of parameters, Bosonic Dynamical Mean-Field Theory (B-DMFT) has been developed [2]. This formalism enables one to treat condensed and normal Bosons on equal footing. B-DMFT investigation of Bose-Bose mixture provides different magnetic orders at zero temperature as well as finite temperature. These results are highly relevant to ongoing experiments exploring quantum magnetism for Bosons. Indeed quantum magnetism for Bosons turned out to be more feasable respect to Fermions. The reason is that the cooling process for Fermions is much more challenging and reaching the low temperature in which magnetic orders appear remains elusive.
[1] E. Altman, W. Hofstetter, E. Demler and M. Lukin, New J. Phys. 5, 113 (2003)
[2] A. Hubener, M. Snoek, and W. Hofstetter, Phys. Rev. B 80, 245109 (2009)
