86 research outputs found
Ground states of trapped spin-1 condensates in magnetic field
We consider a spin-1 Bose-Einstein condensate trapped in a harmonic potential
under the influence of a homogeneous magnetic field. We investigate spatial and
spin structure of the mean-field ground states under constraints on the number
of atoms and the total magnetization. We show that the trapping potential can
make the antiferromagnetic condensate separate into three, and ferromagnetic
condensate into two distinct phases. In the ferromagnetic case, the
magnetization is located in the center of the harmonic trap, while in the
antiferromagnetic case magnetized phases appear in the outer regions. We
describe how the transition from the Thomas-Fermi regime to the single-mode
approximation regime with decreasing number of atoms results in the
disappearance of the domains. We suggest that the ground states can be created
in experiment by adiabatically changing the magnetic field strength
Phase ordering kinetics of a nonequilibrium exciton-polariton condensate
We investigate the process of coarsening via annihilation of vortex-antivortex pairs, following the quench to the condensate phase in a nonresonantly pumped polariton system. We find that the late-time dynamics is an example of universal phase-ordering kinetics, characterized by scaling of correlation functions in time. Depending on the parameters of the system, the evolution of the characteristic length scale L(t) can be the same as for the two-dimensional XY model, described by a power law with the dynamical exponent z≈2 and a logarithmic correction, or z≈1 which agrees with previous studies of conservative superfluids
Dynamics of the modified Kibble-\.Zurek mechanism in antiferromagnetic spin-1 condensates
We investigate the dynamics and outcome of a quantum phase transition from an
antiferromagnetic to phase separated ground state in a spin-1 Bose-Einstein
condensate of ultracold atoms. We explicitly demonstrate double universality in
dynamics within experiments with various quench time. Furthermore, we show that
spin domains created in the nonequilibrium transition constitute a set of
mutually incoherent quasicondensates. The quasicondensates appear to be
positioned in a semi-regular fashion, which is a result of the conservation of
local magnetization during the post-selection dynamics
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