Bose Gases near Unitarity

Weiran Li, Tin-Lun Ho
2012 Physical Review Letters  
We study the properties of strongly interacting Bose gases at the density and temperature regime when the three-body recombination rate is substantially reduced. In this regime, one can have a Bose gas with all particles in scattering states (i.e. the "upper branch") with little loss even at unitarity over the duration of the experiment. We show that because of bosonic enhancement, pair formation is shifted to the atomic side of the original resonance (where scattering length a_s<0), opposite
more » ... the fermionic case. In a trap, a repulsive Bose gas remains mechanically stable when brought across resonance to the atomic side until it reaches a critical scattering length a_s^∗<0. For a_s<a_s^∗, the density consists of a core of upper branch bosons surrounded by an outer layer of equilibrium phase. The conditions of low three-body recombination requires that the particle number N<α (T/ω)^5/2 in a harmonic trap with frequency ω, where α is a constant.
doi:10.1103/physrevlett.108.195301 pmid:23003053 fatcat:6m7uwy5uwncbzgn2teg5jy7g3a