Quantum Matter Seminar

Quantum thermalization describes how closed quantum systems can effectively reach thermal equilibrium, reconciling the unitary nature of quantum mechanics with the irreversible entropy growth mandated by the second law of thermodynamics. Despite its ubiquity and significance in fundamental physics, a rigorous theoretical foundation for quantum thermalization has remained elusive for several decades, except in certain special cases. In this talk, I will present our recent results showing that quantum thermalization must occur in any qubit system with local interactions, given three conditions: (i) high effective temperature, (ii) translational invariance, and (iii) absence of perfect resonances in the energy spectrum. Unlike previous works, our proof neither breaks the locality of quantum dynamics nor relies on additional assumptions or empirical models such as the eigenstate thermalization hypothesis (ETH) or random matrix theory. An important implication of our results is that statistical physics can be understood as an emergent phenomenon, explicitly derived from the first principles of quantum mechanics for a large class of systems.