Dresden 2011 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 57: Poster 3: Quantengase, Ultrakalte Atome, Ultrakalte Moleküle, Materiewellen Optik, Präzisionsmessungen, Metrologie
Q 57.45: Poster
Donnerstag, 17. März 2011, 16:30–19:30, P1
Non-Equilibrium Phase Transition of Ultracold Bosons in an Optical Lattice Coupled to a BEC Reservoir — •Mathias Hayn1 and Axel Pelster2 — 1Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — 2Fachbereich Physik, Universität Duisburg-Essen, Lotharstrasse 1, 47048 Duisburg, Germany
Recently, a promising quantum optical realization for a driven-dissipative many-body system of bosons in a lattice
was proposed [1], in which the competition of unitary Hamiltonian and
dissipative Liouvillian dynamics leads to a non-equilibrium phase transition [2].
At first, we give a detailed derivation of this model, based on microscopic Hamiltonians for both bosons in an
optical lattice and for a bath in form of
a weakly interacting Bose gas. We obtain the result that the dynamics of the bosons in the optical
lattice can be described by a master equation in Linblad form, with the dissipative coupling being non-zero
only in one dimension. Afterwards, we convert the master equation into a hierarchy of moment
equations, which is approximately solved. In the limit of small particle densities we are able to
determine, in accordance with the findings of Ref. [2], the order parameter as well as the critical interaction strength,
which characterise the onset of a non-equilibrium phase transition from a thermal to a superfluid state.
[1] S. Diehl, A. Micheli, A. Kantian, B. Kraus, H.P. Büchler, and P. Zoller,
Nature Phys. 4, 878 (2008).
[2] S. Diehl, A. Tomadin, A. Micheli, R. Fazio, and P. Zoller, Phys. Rev. Lett. 105, 015702 (2010).