Physics (Internal)

Quantum thermalization through entanglement

This event is part of the Condensed Matter Theory Seminar Series.

Entanglement within a many-body system is a defining feature of strongly correlated quantum systems. Recent theoretical developments point to the entropy of entanglement as a means to classify unusual quantum phases, such as spin liquids and topological phases. In this talk I will present an experimental scheme to probe entanglement in itinerant systems through interference of two copies of a many-body state. Akin to Hong-Ou-Mandel interference of photons, this measurement performed with ultracold atoms probes the indistinguishability of quantum states. I will discuss how this interference allows us to measure quantum purity, second order Rényi (entanglement) entropy and mutual information within finite Bose-Hubbard chains. In the context of these techniques, I will focus on our investigation of the dynamics of quenched, isolated bosonic systems. Here we observe that thermal ensembles appear to emerge from a pure quantum state, while the entanglement entropy quantitatively approaches the thermal entropy. Our observations experimentally illustrate the role of entanglement in facilitating thermalization of pure systems undergoing unitary dynamics.