Quantum phase fluctuations in an array of mesoscopic Josephson junctions |
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Authors: | A I Belousov Yu E Lozovik |
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Institution: | (1) Institute of Spectroscopy, Russian Academy of Sciences, 142092 Troitsk, Moscow Region, Russia |
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Abstract: | The effects of macroscopic ordering in a system of mesoscopic Josephson junctions are investigated by the quantum Monte Carlo
simulation technique (using path integrals). The phase diagram of the system in the T-q plane (q is the dimensionless quantum parameter
, where J is the Josephson coupling constant and C
0 is the self-capacitance of the granules) is investigated in detail. An analysis of the behavior of the relative root-mean-square
phase shifts, as well as the helicity and vorticity moduli, demonstrates the need to employ these two quantities as the parameters
which most completely reflect the character of the topological phase transition in the quantum system under consideration.
Two methods are proposed for calculating the vorticity modulus: 1) a modification of the Gibbs-Bogolyubov variational principle
for calculating the free energy change in response to alteration of the type of boundary conditions; 2) calculation of the
response to the introduction of an infinitesimal magnetic flux at some point in the system. The calculations confirm the absence
of reentrant melting and phase transitions of a non-Kosterlitz-Thouless type in the region of strong quantum phase fluctuations
q>1.
Fiz. Tverd. Tela (St. Petersburg) 39, 1513–1519 (September 1997) |
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