A silicon quantum-dot-coupled nuclear spin qubit

Single nuclear spins in the solid state have long been envisaged as a platform for quantum computing. However, establishing long-range interactions between multiple dopants or defects is challenging. Conversely, in lithographically-defined quantum dots, tunable interdot electron tunneling allows direct coupling of electron spin-based qubits in neighboring dots. Moreover, compatibility with semiconductor fabrication techniques provides a compelling route to scaling. Unfortunately, hyperfine interactions are typically too weak to address single nuclei. In this presentation, we report that for electrons in silicon metal-oxide-semiconductor quantum dots the hyperfine interaction is sufficient to initialize, read-out and control single silicon-29 nuclear spins, yielding a combination of the long coherence times of nuclear spins with the flexibility and scalability of quantum dot systems. We demonstrate that the nuclear and electron spins can be entangled and that they both retain their coherence while moving the electron between quantum dots, paving the way to long range nuclear-nuclear entanglement via electron shuttling. Our results establish nuclear spins in quantum dots as a powerful new resource for quantum processing [1].

[1] B. Hensen et al, arXiv:1904.08260.