Time-dependent universal conductance fluctuations in mesoscopic Au wires: implications

TL;DR

This study investigates time-dependent conductance fluctuations in gold nanowires, revealing inconsistencies with existing theories and suggesting potential impacts on quantum decoherence understanding.

Contribution

The paper provides new experimental insights into TDUCF in Au nanowires and questions the validity of current theoretical assumptions about frequency dependence.

Findings

Inconsistencies between $L_{\,phi}^{WL}$ and $L_{\,phi}^{TDUCF}

TDUCF may deviate from $1/f$ frequency dependence at high frequencies

Implications for decoherence in solid-state qubits

Abstract

In cold, mesoscopic conductors, two-level fluctuators lead to time-dependent universal conductance fluctuations (TDUCF) manifested as $1/f$ noise. In Au nanowires, we measure the magnetic field dependence of TDUCF, weak localization (WL), and magnetic field-driven (MF) UCF before and after treatments that alter magnetic scattering and passivate surface fluctuators. Inconsistencies between $L_{\phi}^{\rm WL}$ and $L_{\phi}^{\rm TDUCF}$ strongly suggest either that the theory of these mesoscopic phenomena in weakly disordered, highly pure Au is incomplete, or that the assumption that the TDUCF frequency dependence remains $1/f$ to very high frequencies is incorrect. In the latter case, TDUCF in excess of $1/f$ expectations may have implications for decoherence in solid-state qubits.