Classical and quantum descriptions of the Kac ring model

Johannes M. Oberreuter, Ingo Homrighausen, Stefan K. Kehrein

Eric A. Carlen, Maria C. Carvalho, Michael Loss

G. Costache

Niamat Gill, Nishchal Dwivedi

Statistical physics is important in understanding the physics of interacting many bodies. This has been historically developed by attempts to understand colliding gases and quantifying quantities like entropy, free energy, and other thermodynamic quantities. An important contribution in statistical physics was by Boltzmann in the form of the H-theorem, which considered collisions between particles and used the assumption of molecular chaos or Stosszahlansatz to understand macroscopic irreversibility. To elucidate these ideas, Mark Kac introduced a classical analog called Kac rings. In this work, we attempt to introduce quantum-ness in a Kac ring and study its entropy and recurrence, comparing and contrasting to corresponding trends in a classical Kac ring. We look at the trends of recurrence time for a system with a qubit as a pointer. We further study the time distribution of entropy for these systems.

A. Muriel

Using a pedagogical model introduced by Dresden and Feiock, the quantum mechanical version of the Kac ring model, the following studies are illustrated: (a) solution of the Liouville equation using projection techniques; (b) analysis of the difference between the linear and nonlinear theories; and (c) existence of a kinetic description, with the solution of the Pauli master equation for this example.

Max Dresden