Strong coupling of a spin qubit to a superconducting stripline cavity

TL;DR

This paper demonstrates the potential for strong coupling between electron spins in quantum dots and superconducting stripline cavities, enabling advances in quantum information processing with feasible experimental parameters.

Contribution

It proposes a method to achieve strong spin-photon coupling using either spin-orbit interaction or magnetic field gradients in quantum dots within superconducting cavities.

Findings

Coupling strength of about 1 MHz predicted.

Strong coupling regime achievable with isotopically purified Si dots.

Parameters based on existing devices suggest experimental feasibility.

Abstract

We study electron-spin-photon coupling in a single-spin double quantum dot embedded in a superconducting stripline cavity. With an external magnetic field, we show that either a spin-orbit interaction (for InAs) or an inhomogeneous magnetic field (for Si and GaAs) could produce a strong spin-photon coupling, with a coupling strength of the order of 1 MHz. With an isotopically purified Si double dot, which has a very long spin coherence time for the electron, it is possible to reach the strong-coupling limit between the spin and the cavity photon, as in cavity quantum electrodynamics. The coupling strength and relaxation rates are calculated based on parameters of existing devices, making this proposal experimentally feasible.