  We calculate the mesoscopic admittance $G(\omega)$ of a double quantum dot
(DQD),which can be measured directly using microwave techniques. This quantity
reveals spectroscopic information on the DQD and is also directly sensitive to
a Pauli spin blockade effect. We then discuss the problem of a DQD coupled to a
high quality photonic resonator. When the photon correlation functions can be
developed along a random-phase-approximation-like scheme, the response of the
resonator gives an access to $G(\omega)$.
