Date/Time
Date(s) - 01/02/2006
3:30 pm - 4:30 pm

Title: Living in dimension lower than meets the eye: Sliding phases in classical and quantum statistical mechanics

Speaker: Dr. Sumanta Tewari

Institute: University of Maryland
Department of Physics

Location: ABB 102

Description:

Sliding phases are phases that, in spite of living in a nominally higher dimension, possess surprising
characteristics of a lower dimensionality. They have been discussed before in classical statistical mechanics in relation to biology, and in quantum statistical mechanics in relation to the cuprate superconductors. Here, I shall consider Josephson junction arrays in the presence of external dissipation, a prototype relevant to a host of problems including granular superconductivity and quantum computation, and show that the normal phase in this quantum system is an unusual sliding phase. In this phase, the states of the local (0+1) – dimensional elements (single Josephson junctions) can slide past each other with no energy cost despite arbitrary-range spatial couplings among them. The normal-superconductor quantum phase transition (QPT), tunable by varying the strength of dissipation, is thus essentially governed by local physics, even though the underlying system is an extended one in any dimension. The unusual character of the sliding phase and the associated QPT can be tested by measuring the current-voltage characteristics. This may be the simplest and the most natural example of a sliding phase in nature.