Persistent currents in nanorings and quantum decoherence by Coulomb interaction

Abstract

Employing instanton technique we evaluate equilibrium persistent current (PC) produced by a quantum particle moving in a periodic potential on a ring and interacting with a dissipative environment formed by diffusive electron gas. The model allows for detailed non-perturbative analysis of interaction effects and -- depending on the system parameters -- yields a rich structure of different regimes. We demonstrate that at low temperatures PC is exponentially suppressed at sufficiently large ring perimeters $2\pi R>L_{\phi }$ where the dephasing length $L_{\phi }$ is set by interactions and does not depend on temperature. This behavior represents a clear example of quantum decoherence by electron-electron interactions at $T\to 0$.

13 pages, 4 figures

References in corpus (3)

• Quantum decoherence of interacting electrons in arrays of quantum dots and diffusive conductors
• Weak localization in a system with a barrier: Dephasing and weak Coulomb blockade
• Aharonov-Bohm oscillations in coupled quantum dots: Effect of electron-electron interactions