Quantum thermalization through entanglement in an isolated many-body system

Statistical mechanics relies on the maximization of entropy in a system at thermal equilibrium. However, an isolated quantum many-body system initialized in a pure state remains pure during Schrödinger evolution, and in this sense it has static, zero entropy. We experimentally studied the emergence of statistical mechanics in a quantum state and observed the fundamental role of quantum entanglement in facilitating this emergence. Microscopy of an evolving quantum system indicates that the full quantum state remains pure, whereas thermalization occurs on a local scale. We directly measured entanglement entropy, which assumes the role of the thermal entropy in thermalization. The entanglement creates local…

• NS
  National Science Foundation
• GA
  Gordon and Betty Moore Foundation

  Award: GBMF3795
• AF
  Air Force Office of Scientific Research
• AR
  Army Research Office