Cavity QED with hybrid nanocircuits: from atomic-like physics to condensed matter phenomena

TL;DR

This paper reviews the advancements in mesoscopic circuit QED, highlighting how hybrid nanocircuits coupled with microwave cavities enable exploration of quantum phenomena in condensed matter systems, including artificial atoms and exotic states.

Contribution

It provides a comprehensive overview of experimental and theoretical progress in mesoscopic QED, emphasizing new capabilities to manipulate and probe electronic states in hybrid nanocircuits.

Findings

Demonstration of cavity QED techniques with hybrid nanocircuits.

Observation of electron tunneling dynamics via cavity photons.

Potential to study exotic states like Majorana bound states.

Abstract

Circuit QED techniques have been instrumental to manipulate and probe with exquisite sensitivity the quantum state of superconducting quantum bits coupled to microwave cavities. Recently, it has become possible to fabricate new devices where the superconducting quantum bits are replaced by hybrid mesoscopic circuits combining nanoconductors and metallic reservoirs. This mesoscopic QED provides a new experimental playground to study the light-matter interaction in electronic circuits. Here, we present the experimental state of the art of Mesoscopic QED and its theoretical description. A first class of experiments focuses on the artificial atom limit, where some quasiparticles are trapped in nanocircuit bound states. In this limit, the Circuit QED techniques can be used to manipulate and probe electronic degrees of freedom such as confined charges, spins, or Andreev pairs. A second class of experiments consists in using cavity photons to reveal the dynamics of electron tunneling between a nanoconductor and fermionic reservoirs. For instance, the Kondo effect, the charge relaxation caused by grounded metallic contacts, and the photo-emission caused by voltage-biased reservoirs have been studied. The tunnel coupling between nanoconductors and fermionic reservoirs also enable one to obtain split Cooper pairs, or Majorana bound states. Cavity photons represent a qualitatively new tool to study these exotic condensed matter states.