Simulation of inhomogeneous distributions of ultracold atoms in an optical lattice via a massively parallel implementation of nonequilibrium strong-coupling perturbation theory

Dirks, Andreas and Mikelsons, Karlis and Krishnamurthy, HR and Freericks, James K (2014) Simulation of inhomogeneous distributions of ultracold atoms in an optical lattice via a massively parallel implementation of nonequilibrium strong-coupling perturbation theory. In: PHYSICAL REVIEW E, 89 (2).

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Abstract

We present a nonequilibrium strong-coupling approach to inhomogeneous systems of ultracold atoms in optical lattices. We demonstrate its application to the Mott-insulating phase of a two-dimensional Fermi-Hubbard model in the presence of a trap potential. Since the theory is formulated self-consistently, the numerical implementation relies on a massively parallel evaluation of the self-energy and the Green's function at each lattice site, employing thousands of CPUs. While the computation of the self-energy is straightforward to parallelize, the evaluation of the Green's function requires the inversion of a large sparse 10(d) x 10(d) matrix, with d > 6. As a crucial ingredient, our solution heavily relies on the smallness of the hopping as compared to the interaction strength and yields a widely scalable realization of a rapidly converging iterative algorithm which evaluates all elements of the Green's function. Results are validated by comparing with the homogeneous case via the local-density approximation. These calculations also show that the local-density approximation is valid in nonequilibrium setups without mass transport.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW E
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copyright for this article belongs to the AMER PHYSICAL SOC, USA
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	15 Apr 2014 06:32
Last Modified:	15 Apr 2014 06:33
URI:	http://eprints.iisc.ac.in/id/eprint/48859

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