Electron-photon coupling in mesoscopic quantum electrodynamics
Résumé
Understanding the interaction between cavity photons and electronic nanocircuits is crucial for the development
of mesoscopic quantum electrodynamics (QED). One has to combine ingredients from atomic cavity QED,
such as orbital degrees of freedom, with tunneling physics and strong cavity field inhomogeneities, specific to
superconducting circuit QED. It is therefore necessary to introduce a formalism which bridges between these
two domains.We develop a general method based on a photonic pseudopotential to describe the electric coupling
between electrons in a nanocircuit and cavity photons. In this picture, photons can induce simultaneously orbital
energy shifts, tunneling, and local orbital transitions. We study in detail the elementary example of a single
quantum dot with a single normal metal reservoir, coupled to a cavity. Photon-induced tunneling terms lead
to a nonuniversal relation between the cavity frequency pull and the damping pull. Our formalism can also be
applied to multiple quantum dot circuits, molecular circuits, quantum point contacts, metallic tunnel junctions,
and superconducting nanostructures enclosing Andreev bound states or Majorana bound states, for instance.