Characterisation of Phosphorus and Arsenic Dopant Quantum Devices in Silicon

Dopants in silicon have demonstrated exceptionally long coherence times and can benefit from the scalability of silicon-based nano-electronic processes. Arsenic dopants also benefit from a 3/2 nuclear spin manifold, allowing qudit encoding on the nuclear spins, which have demonstrated nuclear spin coherence times up to 30 seconds and can act as a quantum memory.

We demonstrate the fabrication of phosphorus and arsenic dopants with atomic-scale precision [1] as single-electron transistors and single dopants on a silicon substrate and the characterisation of DC transport and RF reflectometry measurements on these devices. Our RF reflectometry measurements use variable capacitors (varactors) to impedance match RLC circuits connected to the qubits to the transmission lines, which allows us to match the quantum capacitance associated with the spin state to the reflection coefficient of the RF signals.