부산대학교 도서관

Modelling the electrical response of multi-level quantum systems at finite frequency has been typically performed in the context of two incomplete paradigms: (i) Input-output theory, which is valid at any frequency but neglects dynamic losses, and (ii) semiclassical theory, which captures well dynamic dissipation effects but is only accurate at low frequencies. Here, we develop a unifying theory, valid for arbitrary frequencies, that captures the non-unitary effects introduced by finite relaxation and dephasing. The theory allows a multi-level system to be described by a universal small-signal equivalent circuit model, a resonant RLC circuit, whose topology only depends on the number of energy levels, which we apply here to the case of a charge qubit in a double quantum dot. Our model will facilitate the design of hybrid quantum-classical circuits and the simulation of qubit control and quantum state readout.