Optomechanical quantum bus for donor spins in silicon

Donor spins in silicon are a promising platform for quantum information, combining good quantum properties (coherence times, gate fidelities) with the strong industrial know-how of silicon fabrication. Their application potential is, however, somewhat constrained by the lack of an optical interface, and considerable attention has been recently focused on spin-photon interfaces in silicon. Unfortunately, the most studied and best-known donor qubits (phosphorous, bismuth) do not possess optical transitions.

To address this, we aim to develop an optomechanical bridge between the donor spin qubits and telecom-wavelength photons. We couple the spin qubit to the mechanical motion of a nanoresonator, whose motion in turn influences the resonance frequency of an optical cavity. This allows reading out the qubit state with a telecom wavelength laser. The mechanical system can also be used to couple spins to each other in a controlled way.



In this talk, I will present the fundamental concepts for such a proposal and numerical simulations regarding its implementation in a practical system of silicon nanobeams implanted with donors. I will also present preliminary experimental data on our current progress towards characterizing the optomechanical resonators with embedded spins [1] and developing auxiliary spin readout methods [2] to be used with the nanobeams.

[1] C. Shakespeare et al., Mater. Quantum. Technol. 1, 045003 (2021)

[2] T. Loippo et al, Phys. Rev. Materials 7, 016202 (2023).