Zero-Point Fluctuations and the Quenching of the Persistent Current in Normal Metal Rings

TL;DR

This paper studies how zero-point quantum fluctuations, influenced by environmental impedance, suppress the persistent current in mesoscopic rings with quantum dots, highlighting the role of displacement currents and dynamical fluctuations.

Contribution

It demonstrates that zero-point fluctuations can significantly quench persistent currents in mesoscopic systems, emphasizing the impact of environmental impedance and displacement currents.

Findings

Zero-point fluctuations suppress persistent current as external impedance decreases.

Dynamical fluctuations can surpass the average persistent current at low impedance.

Displacement currents play a crucial role in current fluctuations.

Abstract

The ground state of a phase-coherent mesoscopic system is sensitive to its environment. We investigate the persistent current of a ring with a quantum dot which is capacitively coupled to an external circuit with a dissipative impedance. At zero temperature, zero-point quantum fluctuations lead to a strong suppression of the persistent current with decreasing external impedance. We emphasize the role of displacement currents in the dynamical fluctuations of the persistent current and show that with decreasing external impedance the fluctuations exceed the average persistent current.