Quantum fluctuations in the equilibrium state of a thin superconducting loop

F. W. J. Hekking; L. I. Glazman

doi:10.1103/PhysRevB.55.6551

← Back to search

Quantum fluctuations in the equilibrium state of a thin superconducting loop

F. W. J. Hekking, L. I. Glazman

DOI 10.1103/PhysRevB.55.6551 · Physical Review B

T1

Active bibliographic source — not scientific approval

Bibliographic access preserves source history; it does not approve extracted materials or validate reported claims. Review warnings on each occurrence separately.

Abstract

We study the oscillatory flux dependence of the supercurrent in a thin superconducting loop, closed by a Josephson junction. Quantum fluctuations of the order parameter in the loop affect the shape and renormalize the amplitude of the supercurrent oscillations. In a short loop, the amplitude of the sinusoidal flux dependence is suppressed. In a large loop, the supercurrent shows a sawtooth dependence on flux in the classical limit. Quantum fluctuations not only suppress the amplitude of the oscillations, but also smear the cusps of the sawtooth dependence. The oscillations approach a sinusoidal form with increasing fluctuation strength. At any finite length of the loop, the renormalized current amplitude is finite. This amplitude shows a power-law dependence on the junction conductance, with an exponent depending on the low-frequency impedance of the loop.