Volume 81, Number 3, February 2008
Article Number 30001
Number of page(s) 5
Section General
Published online 19 December 2007
EPL, 81 (2008) 30001
DOI: 10.1209/0295-5075/81/30001

Decoherence of a particle in a ring

D. Cohen and B. Horovitz

Department of Physics, Ben Gurion University - Beer Sheva 84105, Israel

received 13 July 2007; accepted in final form 21 November 2007; published February 2008
published online 19 December 2007

We consider a particle coupled to a dissipative environment and derive a perturbative formula for the dephasing rate based on the purity of the reduced probability matrix. We apply this formula to the problem of a particle on a ring, that interacts with a dirty-metal environment. At low but finite temperatures we find a dephasing rate $\propto T^{3/2}$, and identify dephasing lengths for large and for small rings. These findings shed light on recent Monte Carlo data regarding the effective mass of the particle. At zero temperature we find that spatial fluctuations suppress the possibility of having a power law decay of coherence.

03.65.Yz - Decoherence; open systems; quantum statistical methods.
74.40.+k - Fluctuations (noise, chaos, nonequilibrium superconductivity, localization, etc.).
73.23.-b - Electronic transport in mesoscopic systems.

© EPLA 2008