Microwave quantum optics and electron transport through a metallic dot strongly coupled to a transmission line cavity

TL;DR

This paper provides a theoretical analysis of photon states and electronic transport in a metallic quantum dot coupled to a microwave cavity, revealing non-equilibrium effects and transport signatures at strong coupling.

Contribution

It derives a Hamiltonian for strong capacitive coupling and analyzes photon and electron dynamics, including polaron formation and transport signatures, within the circuit QED framework.

Findings

Identification of microwave polaron signatures in photon states

Observation of superpoissonian shot-noise at ultrastrong coupling

Analysis of intra mode conversion and polaron coherences

Abstract

We investigate theoretically the properties of the photon state and the electronic transport in a system consisting of a metallic quantum dot strongly coupled to a superconducting microwave transmission line cavity. Within the framework of circuit quantum electrodynamics we derive a Hamiltonian for arbitrary strong capacitive coupling between the dot and the cavity. The dynamics of the system is described by a quantum master equation, accounting for the electronic transport as well as the coherent, non-equilibrium properties of the photon state. The photon state is investigated, focusing on, for a single active mode, signatures of microwave polaron formation and the effects of a non-equilibrium photon distribution. For two active photon modes, intra mode conversion and polaron coherences are investigated. For the electronic transport, electrical current and noise through the dot and the influence of the photon state on the transport properties are at the focus. We identify clear transport signatures due to the non-equilibrium photon population, in particular the emergence of superpoissonian shot-noise at ultrastrong dot-cavity couplings.