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

In cold, mesoscopic conductors, two-level fluctuators lead to time-dependent universal conductance fluctuations (TDUCFs) manifested as 1∕f noise. In Au nanowires, we measure the magnetic-field dependence of TDUCFs, weak localization (WL), and magnetic-field-driven UCFs before and after treatments that alter magnetic scattering and passivate surface fluctuators. Inconsistencies between L_ϕ^WL and L_ϕ^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, TDUCFs in excess of 1∕f expectations may have implications for decoherence in solid-state qubits.