Ever since the introduction of quantum mechanics, physicists have been puzzled by how such a theory can explain the experimental fact that systems out of equilibrium evolve towards equilibrium and can then be described utilizing statistical mechanics. In an article published in Physical Review Letters, a team lead by Prof. Marcos Rigol explained how this works for a rare class of systems that live in one dimension.

The team, which includes NIST physicists Amy Cassidy and Charles Clark, argued that the emergence of statistical behavior is the result of a generic underlying property of many-particle quantum systems. The results were obtained by a combination of analytical insights and numerical calculations in which up to 10¹⁰ eigenstates of a lattice model had to be studied.