Quantum systems equilibrate rapidly for most observables

Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Jul;90(1):012121. doi: 10.1103/PhysRevE.90.012121. Epub 2014 Jul 22.

Abstract

Considering any Hamiltonian, any initial state, and measurements with a small number of possible outcomes compared to the dimension, we show that most measurements are already equilibrated. To investigate nontrivial equilibration, we therefore consider a restricted set of measurements. When the initial state is spread over many energy levels, and we consider the set of observables for which this state is an eigenstate, most observables are initially out of equilibrium yet equilibrate rapidly. Moreover, all two-outcome measurements, where one of the projectors is of low rank, equilibrate rapidly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Quantum Theory*
  • Temperature