Strong coupling between an electron in a quantum dot circuit and a photon in a cavity

TL;DR

This paper demonstrates the first strong coupling between a single electron in a quantum dot circuit and microwave photons, enabling coherent light-matter hybridization and potential advances in quantum information processing.

Contribution

It reports the experimental realization of strong coupling in a superconductor-quantum dot circuit, a significant step forward from previous weak coupling regimes.

Findings

Observed vacuum Rabi splitting of ~10 MHz

Coupling exceeds linewidth by a factor of 3

Pathway to long-distance entanglement of quantum dot qubits

Abstract

Circuit quantum electrodynamics allows one to probe, manipulate and couple superconducting quantum bits using cavity photons at an exquisite level. One of its cornerstones is the possibility to achieve the strong coupling which allows one to hybridize coherently light and matter. Its transposition to quantum dot circuits could offer the opportunity to use new degrees of freedom such as individual charge or spin. However, the strong coupling of quantum dot circuits to cavity photons remains to be observed. Here, we demonstrate a hybrid superconductor-quantum dot circuit which realizes the strong coupling of an individual electronic excitation to microwave photons. We observe a vacuum Rabi splitting 2g~10 MHz which exceeds by a factor of 3 the linewidth of the hybridized light-matter states. Our findings open the path to ultra-long distance entanglement of quantum dot based qubits. They could be adapted to many other circuit designs, shedding new light on the roadmap for scalability of quantum dot setups.