Detection of persistent current correlation in cavity-QED

We simulated the radiative response of a cavity quantum electrodynamics (QED) inductively coupled to the ring pierced by magnetic flux and analyzed its spectral dependence to get insight into persistent current dynamics. Current fluctuations in the ring induce changes in the microwave resonator: shifting the resonant frequency and changing its damping. We use the linear response theory and calculate the current response function by means of the Green function technique. Our model contains two quantum dots which divide the ring into two arms with different electron transfers. There are two opposite (symmetric and asymmetric) components of the persistent current, which interplay can be observed the response functions. The resonator reflectance shows characteristic shifts in the dispersive regime and avoided crossings at the resonance points. The magnitude of the resonator frequency shift is greater for coupling to the arm with higher transparency. Fluctuations of the symmetric component of the persistent current are relevant for a wide range of the Aharonov-Bohm phase phi, while the asymmetric component becomes dominant close to phi approximate to pi (when the total persistent current changes its orientation).