Faculty @ Max Planck Institute for Quantum Optics, Germany
Friday July 1 – 10.45 BST
Quantum many-body systems in thermal equilibrium: correlations and classical simulation
There are numerous models of interacting many-body quantum systems whose physics we would like to probe and better understand. This notably includes situations in which the systems at hand are at thermal equilibrium with its environment.
Due to the inherent complexity of quantum mechanics, one might expect that those equilibrium states will typically be very complex, and hard to describe via direct means or classical algorithms. At the same time, the effect of thermal fluctuations, together with our intuition from thermodynamics, point in the opposite direction: a system at equilibrium should have a simple description.
In this talk, we aim to clarify the product of this tension. To do so, we explain how and when quantum systems in thermal equilibrium can be shown to have simpler features and descriptions than general quantum states. This includes mathematical results on the nature of the internal correlations of these systems, such as area laws, as well as provably efficient classical algorithms for their description, mostly involving tensor networks.