Topological phase transition in 2D quantum Josephson array

Path Integral Quantum Monte Carlo Simulation is used to study thermodynamic properties and a phase diagram of 2D quantum Josephson array, described by 2+1 XY model. The helicity and vorticity moduli, correlation function of phases and other characteristics of the system as functions of quantum parameter q and temperature T are studied (q = (h) over bar/root JC), J is the Josephson coupling constant, C is the intragrain capacitance). Quantum fluctuation induced superconductor-normal phase transition is studied in detail through the use of behavior of above-mentioned quantities. No discontinuous or reentrant phase transition in q-T plane is found. Analysis of the vorticity and the renormalized coupling constant leads to the conclusion that the whole line of phase transition is of Kosterlitz-Thouless type. Copyright (C) 1996 Elsevier Science Ltd