An extensible computational toolbox for ultracold atoms

Time: 1pm AEST - Melbourne, Sydney, Canberra, Brisbane; 3pm NZST.

Speaker: Professor Joachim Brand
Affiliation: New Zealand Institute for Advanced Study, Massey University, Auckland

Abstract

Over the past few years we have been developing methods for simulating strongly correlated few and many-body quantum systems and have built an associated open-source software library. At the heart of the project is a quantum Monte Carlo method (full configuration interaction quantum Monte Carlo) that extends the reach of the extremely versatile exact diagonalisation method to larger quantum systems. While primarily directed at quantum ground states, the approach has been extended to studying excited states, real-time evolution, and driven-dissipative open quantum systems.

In this talk I will introduce the Monte Carlo algorithm and discuss some insights obtained recently by modeling the algorithm with stochastic differential equations. The transcorrelated method allows us to deal efficiently with wave function singularities due to short-range interactions. I will highlight a recent application to the polaron-depleton transition of a mobile impurity in a one-dimensional Bose gas. To finish off, an outlook will be provided on understanding the surprisingly long lifetime of three atoms observed in an optical tweezer trap.