The statistical mechanical description of small systems staying in thermal equilibrium with an
environment can be achieved by means of the Hamiltonian of mean force. In contrast to the …

We review the general aspects of the concept of temperature in equilibrium and non-
equilibrium statistical mechanics. Although temperature is an old and well-established …

Deriving the laws of thermodynamics from a microscopic picture is a central quest of
statistical mechanics. This tutorial focuses on the derivation of the first and second law for …

We perform an experiment in which a quantum heat engine works under two reservoirs, one
at a positive spin temperature and the other at an effective negative spin temperature, ie …

Do negative absolute temperatures matter physics and specifically Statistical Physics? We
provide evidence that we can certainly answer positively to this vexata quaestio. The great …

Temperature is usually defined for physical systems at thermal equilibrium. Nevertheless
one may wonder if it would be possible to attribute a meaningful notion of temperature to an …

Describing open quantum systems far from equilibrium is challenging, in particular when the
environment is mesoscopic, when it develops nonequilibrium features during the evolution …

Negative absolute temperatures were introduced into experimental physics by Purcell and
Pound, who successfully applied this concept to nuclear spins; nevertheless, the concept …

We investigate how the temperature calculated from the microcanonical entropy compares
with the canonical temperature for finite isolated quantum systems. We concentrate on …

The validity of the concept of negative temperature has been recently challenged by arguing
that the Boltzmann entropy (that allows negative temperatures) is inconsistent from a …