# Strong Coupling Cavity QED with Gate-Defined Double Quantum Dots Enabled by a High Impedance Resonator

## TL;DR

This paper demonstrates strong coupling between a double quantum dot and a high impedance resonator, achieving vacuum Rabi splitting, which advances the potential for quantum information processing in semiconductor nanostructures.

## Contribution

It introduces a high impedance resonator coupled to a double quantum dot, achieving strong coupling and resolving vacuum Rabi splitting in a semiconductor system.

## Key findings

- Vacuum Rabi splitting of 238 MHz observed
- Resonator linewidth measured at 12 MHz
- DQD charge qubit dephasing rate of 80 MHz

## Abstract

The strong coupling limit of cavity quantum electrodynamics (QED) implies the capability of a matter-like quantum system to coherently transform an individual excitation into a single photon within a resonant structure. This not only enables essential processes required for quantum information processing but also allows for fundamental studies of matter-light interaction. In this work we demonstrate strong coupling between the charge degree of freedom in a gate-detuned GaAs double quantum dot (DQD) and a frequency-tunable high impedance resonator realized using an array of superconducting quantum interference devices (SQUIDs). In the resonant regime, we resolve the vacuum Rabi mode splitting of size $2g/2\pi = 238$ MHz at a resonator linewidth $\kappa/2\pi = 12$ MHz and a DQD charge qubit dephasing rate of $\gamma_2/2\pi = 80$ MHz extracted independently from microwave spectroscopy in the dispersive regime. Our measurements indicate a viable path towards using circuit based cavity QED for quantum information processing in semiconductor nano-structures.