Optical Entanglement of Nuclear Spins in Silicon

A major breakthrough in quantum information processing is expected once “qubits”, carriers of quantum information, can be reliably integrated and controlled in silicon – the basis of today’s advanced classical information technology.

Previous qubit realizations used the electronic spin of quantum dots or dopants, i.e. atoms of a different species replacing silicon in the lattice.

However, this approach has only allowed for the entanglement of qubits in immediate proximity, which has hindered increasing the size of silicon-based quantum information processing systems. In OpENSpinS, these limitations will be overcome by using the nuclear spins of erbium dopants as qubits.

These are initialized, read-out and controllably entangled using photons in the minimal-loss band of existing fiber-optical infrastructure.

To demonstrate the unique potential of this approach, the specific objectives of the proposal are: I) The fabrication of nanophotonic resonators with unprecedented Purcell enhancement to enable coherent spin-photon coupling, II) the direct optical addressing and control of nuclear spin qubits with long coherence, and III) the implementation of optically-controlled two-qubit quantum gates and entanglement, both within a node and over distance.

The proposed system combines the advantages of two leading platforms for quantum information processing: the bandwidth and long-distance connectivity of photons at telecommunications wavelength with the robust control and hour-long qubit storage achievable with nuclear spins in silicon.

As the proposed chip-integrated resonators can be manufactured using established processes of the semiconductor industry, the novel hardware platform implemented in OpENSpinS offers unique prospects for future up-scaling of quantum information processing systems and quantum networks.