Physics Research Conference

Electron spins are excellent candidates for solid state quantum computing due to their exceptionally long quantum coherence times, which is a result of weak coupling to environmental degrees of freedom. However, this isolation comes with a cost, as it is difficult to coherently couple two spins in the solid state, especially when they are separated by a large distance. Here we combine a large electric-dipole interaction with spin-orbit coupling to achieve spin-photon coupling [1]. Vacuum Rabi splitting is observed in the cavity transmission as the Zeeman splitting of a single spin is tuned into resonance with the cavity photon. We achieve a spin-photon coupling rate as large as gs/2π = 10 MHz, which exceeds both the cavity decay rate κ/2π = 1.8 MHz and spin dephasing rate γ/2π = 2.4 MHz, firmly anchoring our system in the strong-coupling regime [2]. Moreover, the spin-photon coupling mechanism can be turned off by localizing the spin in one side of the double quantum dot. These developments in quantum dot circuit quantum electrodynamics, combined with recent demonstrations of high-fidelity two-qubit gates in Si, firmly anchor Si as a leading material system in the worldwide race to develop a scalable quantum computer [3]. 1. Mi et al., Science 355, 156 (2017). 2. Mi et al., Nature 555, 599 (2018). 3. Zajac et al., Science 359, 439 (2018).