Awesome news everyone! Our preprint Spin-cQED with bulk germanium spin qubits just got on the arxiv!!

If you have been following our recent works, you already know that unstrained germanium keeps popping up as a promising material for spin-photon interactions thanks to its reduced heavy-hole light-hole splitting. In this work we take the idea seriously and systematically model hole spins in bulk germanium double quantum dots, comparing them against state-of-the-art strained germanium heterostructures. The result: bulk germanium readily reaches the strong-coupling regime with superconducting resonators, with spin-photon coupling strengths beyond 100 MHz stemming from spin-orbit interactions beyond the perturbative regime. As a bonus, the coupling is much less sensitive to the magnetic field orientation, easing operation and mitigating device-to-device variability. Bulk germanium is shaping up as a compelling platform for scalable spin-cQED!