Numerical method for the stochastic projected Gross-Pitaevskii equation

S. J. Rooney; P. B. Blakie; A. S. Bradley

doi:10.1103/physreve.89.013302

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arXiv · 1310.0161

Numerical method for the stochastic projected Gross-Pitaevskii equation

S. J. Rooney·P. B. Blakie·A. S. Bradley

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Abstract

We present a method for solving the stochastic projected Gross-Pitaevskii equation (SPGPE) for a three-dimensional Bose gas in a harmonic-oscillator trapping potential. The SPGPE contains the challenge of both accurately evolving all modes in the low energy classical region of the system, and evaluating terms from the number-conserving scattering reservoir process. We give an accurate and efficient procedure for evaluating the scattering terms using a Hermite-polynomial based spectral-Galerkin representation, which allows us to precisely implement the low energy mode restriction. Stochastic integration is performed using the weak semi-implicit Euler method. We extensively characterize the accuracy of our method, finding a faster than expected rate of stochastic convergence. Physical consistency of the algorithm is demonstrated by considering thermalization of initially random states.

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BibTeX RIS

S. J. Rooney, P. B. Blakie, A. S. Bradley. 2013-10-01. Numerical method for the stochastic projected Gross-Pitaevskii equation. https://doi.org/10.1103/physreve.89.013302

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