title: Isolated nonequilibrium systems in contact.
abstract: We investigate a solvable model for energy-conserving nonequilibrium steady states. The time-reversal asymmetry of the dynamics leads to the violation of detailed balance and to ergodicity breaking, as manifested by the presence of dynamically inaccessible states. Two such systems in contact do not reach the same effective temperature if standard definitions are used. However, we identify the effective temperature that controls energy flow. Although this operational temperature does reach a common value upon contact, the total entropy of the joint system can decrease.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Yair
authors.initials: Y
authors.lastname: Shokef
authors.forename: Gal
authors.initials: G
authors.lastname: Shulkind
authors.forename: Dov
authors.initials: D
authors.lastname: Levine