Modelling quantum thermalization with quantum computers

In quantum computing and simulation, one of our main goals is to efficiently mimic natural physical phenomena in a controlled manner. The process of thermalization i.e. the preparation of thermal states of quantum matter is one such crucial task, for which recently there has been relevant progress. In this talk, we will showcase important parts of this progress by introducing a recent efficiently implementable dissipative evolution that models thermalization in the many-body setting. We then prove two main facts about this dissipative evolution:

1) That in the high temperature regime it is able to efficiently approach thermal equilibrium. This can in turn be used for the efficient estimation of partition functions, and for producing thermofield double states.

2) That in the low temperature regime, this dissipation yields a computational model with the same power as arbitrary quantum computations (BQP-complete).

Taken together, our results show that a family of quasi-local dissipative evolutions efficiently prepares a large class of quantum many-body states of interest, and has the potential to mirror the success of classical Monte Carlo methods.