Photon-mediated electron transport in hybrid circuit-QED

We investigate photon-mediated transport processes in a hybrid circuit-QED structure consisting of two double quantum dots coupled to a common microwave cavity. Under suitable resonance conditions, electron transport in one double quantum dot is facilitated by the transport in the other dot via photon-mediated processes through the cavity. We calculate the average current in the quantum dots, the mean cavity photon occupation, and the current cross-correlations with both a full numerical simulation and a recursive perturbation scheme that allows us to include the influence of the cavity order-by-order in the couplings between the cavity and the quantum dot systems. We can then clearly identify the photon-mediated transport processes. Copyright c © EPLA, 2013 Introduction. – Hybrid structures that combine electronic and photonic degrees of freedom in on-chip circuit-QED architectures are currently undergoing a rapid development [1]. A series of recent experiments [2,3] have shown that controllable coupling between electronic transport in quantum dot structures and a single mode of the electromagnetic field in a microwave cavity is now achievable. Several experiments have realized both a single quantum dot and two tunnel-coupled quantum dots interacting with a microwave resonator [2]. Very recently two quantum dots were successfully coupled to distant parts of a common cavity resonator, and photon-mediated interaction between the spatially separated quantum dot circuits was reported [3]. These experimental advances are now fueling an increasing theoretical interest in understanding and predicting the physics of hybrid circuit-QED structures [1,4]. A number of proposals [5] have already considered the coupling of electronic spins in quantum dots to microwave resonators. In parallel, other works [6] have focused on the influence of cavity resonators on the transport properties of nearby quantum dot systems. A very recent work [7] expands theoretically on the experimental setup from ref. [3] by considering two separated double quantum dots (DQDs) connected to the same cavity mode. With the DQDs weakly coupled to electronic leads at finite voltages, this system displays intriguing Tavis-Cummings physics, Ω 1 ε 1 Γ L1 Γ R1 Ω 2 g 1 g 2 Γ L2 Γ R2 ω c κ, T