Optomechanical resource for fault-tolerant quantum computing

Fusion-based quantum computing with dual-rail qubits is the leading candidate for scalable quantum computing using linear optics. This computing paradigm requires single photons which are entangled into small resource states before being fed into a fusion network. The most popular sources for single optical photons (e.g., spontaneous parametric down-conversion) and for small entangled states (e.g., linear optics) are probabilistic and heralded. It is possible to effect deterministic sources of these photonic resources from many probabilistic, heralded resource generators, but this requires complex optical networks. Alternatively, successfully generated resources can be stored in quantum memories to be retrieved as needed. In this work, we show how optomechanics can be harnessed to implement such quantum memories. The acoustic modes act as caches of quantum resources—single-particle states and even small entangled states—with on-demand read-out. I will show how the resource states can be prepared directly in the acoustic modes using optical controls. This will still be probabilistic and heralded, but the acoustic modes store the quantum states with no extra effort. The quantum states may be transferred from acoustic modes to optical modes, as needed, with another optical drive. The advantages of acoustic modes as optical quantum memories, compared to other technologies, include their intrinsically long lifetimes, as well as being solid state, highly tailorable, and insensitive to electronic or magnetic noise.