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Thursday, June 16, 2016
12:30 PM - 1:30 PM
T-DO Conference Room (TA-3, Bldg 123 Room 121)

Quantum Lunch

Quantum thermalization through entanglement

Adam Kaufman
Department of Physics, Harvard University

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. Adam Kaufman received his undergraduate degree at Amherst College, and recently received his Ph.D. in physics at JILA and the University of Colorado at Boulder. His Ph.D. work focused on quantum control of single atoms in optical tweezers using laser-cooling techniques. He is now a post-doctoral fellow at Harvard University, in the group of Markus Greiner, where he works on microscopy of strongly-interacting systems of lattice-confined bosons.

Host: Sebastian Deffner