Quantum coherence and phase transitions in granular superconductors with dissipation. I. Ordered arrays (original) (raw)
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Quantum fluctuations and dissipative phase transition in granular superconductors
The zero temperature phase diagram of d-dimensional granular superconductors is considered. For small values of Josephson coupling Vcollective long-range quantum fluctuations play the leading role in the destruction of global phase coherence. At V-+0 the critical value of the dimensionless ohmic conductance o, diverges for d< 2 and it is equal to (Y,Z 0.82 for d= 3. For not very small values of V superconductivity may be destroyed by quantum phase slips on inidividual grains. In this case global phase coherence is restored only due to dissipative phase transition. The value of the critical resistance is found to be universal for strongly disordered granular films.
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