Extracts from the Realm of Particles

Theo M. Nieuwenhuizen

The Brownian motion of a harmonically bound quantum particle and coupled to a harmonic quantum bath is exactly solvable. At low enough temperatures the stationary state is non‐Gibbsian due to an entanglement with the bath. This happens when a cloud of bath modes around the particle is formed. Equilibrium thermodynamics for particle plus bath together, does not imply standard thermodynamics for the particle itself at low T. Various formulations of the second law are then invalid. First, the Clausius inequality can be violated. Second, when the width of the confining potential is suddenly changed, there occurs a relaxation to equilibrium during which the rate of entropy production is partly negative. Third, for non‐adiabatic changes of system parameters the rate of energy dissipation can be negative, and, out of equilibrium, cyclic processes are possible which extract work from the bath. Conditions are put forward under which perpetuum mobile of the second kind, having several work extraction cycles, enter the realm of condensed matter physics.

Gabriel Moked, Peter J. Steinberger, Leo Esakia

Theo M. Nieuwenhuizen, ARMEN E. ALLAHVERDYAN

The Brownian motion of a harmonically bound quantum particle and coupled to a harmonic quantum bath is exactly solvable. At low enough temperatures the stationary state is non-Gibbsian due to an entanglement with the bath. This happens when a cloud of bath modes around the particle is formed. Equilibrium thermodynamics for particle plus bath together, does not imply standard thermodynamics for the particle itself at low T. Various formulations of the second law are then invalid. First, the Clausius inequality can be violated. Second, when the width of the confining potential is suddenly changed, there occurs a relaxation to equilibrium during which the rate of entropy production is partly negative. Third, for non-adiabatic changes of system parameters the rate of energy dissipation can be negative, and, out of equilibrium, cyclic processes are possible which extract work from the bath. Conditions are put forward under which perpetuum mobile of the second kind, having several work extraction cycles, enter the realm of condensed matter physics. Introduction. There are not two fundamental theories of nature, quantum mechanics and thermodynamics. There is only one: quantum mechanics, while thermodynamics must emerge from it. The universal character of equilibrium thermodynamics led to the general expectation that in one way or another, thermodynamics will apply to the full

Catherine Brahic, Richard Webb

Dong-Chen Zheng, Yan-Qiang Yu, Renyuan Liao

We develop a method to extract the dissipation for a heavy moving impurity immersed in superfluid Fermi gases, which may serve as a theoretical model to explain relevant experiments. The drag force is derived analytically. As a reward, we are able to extract the density-density correlation function, from which density excitations of the system are carefully examined. We show that dissipations through drag force is associated with two types of excitations, one being single-particle and the other being collective. We map out the critical velocity for dissipation across the Bose-Einstein condensate-Bardeen-Cooper-Schrieffer (BEC-BCS) crossover, consistent with existing experiments. For a magnetic impurity, we show that the dissipation is immune to collective excitations. Our study clearly manifests that dissipation and associated excitations can be controlled by coupling superfluid Fermi gases with a moving impurity, and paves the way for further exploring the intriguing realm of nonequilibrium phenomena and dissipation dynamics.