We investigate flux qubits driven by a biharmonic magnetic signal, with aphase lag that acts as an effective time reversal broken parameter. The drivinginduced transition rate between the ground and the excited state of the fluxqubit can be thought as an effective transmitance, profiting from a directanalogy between interference effects at avoided level crossings and scatteringevents in disordered electronic systems. For time scales prior to fullrelaxation but large compared to the decoherence time, this characteristic ratehas been accessed experimentally and its sensitivity with both the phase lagand the dc flux detuning explored. In this way signatures of UniversalConductance Fluctuations-like effects have recently been analized in fluxqubits and compared with a phenomenological model that only accounts fordecoherence, as a classical noise. We here solve the full dynamics of thedriven flux qubit in contact with a quantum bath employing the Floquet MarkovMaster equation. Within this formalism relaxation and decoherence rates resultstrongly dependent on both the phase lag and the dc flux detuning.Consequently, the associated pattern of fluctuations in the characteristicrates display important differences with those obtained within the mentionedphenomenological model. In particular we demonstrate the Weak Localization-likeeffect in the averages values of the relaxation rate. Our predictions can betested for accessible, but longer time scales than the current experimentaltimes.
展开▼
