Influenciadeundetectornolinealsobreladin´ amicadeun sistemadedosnivelesdisipativo Influence of a nonlinear detector on the dynamics of a dissipative two-level system

We consider a flux qubit inductively coupled to a dc-SQUID (detector); the latter is externally driven by means of a time-dependent periodic field. The external driving allows a description in terms of the quantum Duffing oscillator model. In the Born-Markov regime, we consider the weak coupling between the detector and the surrounding, Ohmic, environment: we mimic the detection of the qubit state through the nonlinear response of the dc-SQUID.