Non-equilibrium dynamics of a Bose-Einstein condensate in an optical lattice

Abstract

The dynamical evolution of a Bose-Einstein condensate trapped in a one-dimensional lattice potential is investigated theoretically in the framework of the Bose-Hubbard model. The emphasis is set on the far-from-equilibrium evolution in a case where the gas is strongly interacting. This is realized by an appropriate choice of the parameters in the Hamiltonian, and by starting with an initial state, where one lattice well contains a Bose-Einstein condensate while all other wells are empty. Oscillations of the condensate as well as non-condensate fractions of the gas between the different sites of the lattice are found to be damped as a consequence of the collisional interactions between the atoms. Functional integral techniques involving self-consistently determined mean fields as well as two-point correlation functions are used to derive the two-particle-irreducible (2PI) effective action. The action is expanded in inverse powers of the number of field components N, and the dynamic equations are derived from it to next-to-leading order in this expansion. This approach reaches considerably beyond the Hartree-Fock-Bogoliubov mean-field theory, and its results are compared to the exact quantum dynamics obtained by A.M. Rey et al., Phys. Rev. A 69, 033610 (2004) for small atom numbers.

9 pages RevTeX, 3 figures

References in corpus (3)

• Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms
• Quantum corrections to the dynamics of interacting bosons: beyond the truncated Wigner approximation
• Nonequilibrium dynamics in the O(N) model to next-to-next-to-leading order in the 1/N expansion

Cited by in corpus (7)

• Finite Temperature Models of Bose-Einstein Condensation
• Quantum versus classical statistical dynamics of an ultracold Bose gas
• Functional renormalisation group approach to far-from-equilibrium quantum field dynamics
• Far-from-equilibrium quantum many-body dynamics
• Ultracold gases far from equilibrium
• Far-from-equilibrium dynamics of an ultracold Fermi gas
• Coarse-Grained Finite-Temperature Theory for the Condensate in Optical Lattices