A single-atom electron spin qubit in silicon

TL;DR

This paper demonstrates the coherent control and measurement of a single electron spin qubit in silicon, showing promising coherence times and compatibility with existing technology for scalable quantum computing.

Contribution

It introduces a method to coherently manipulate and electrically measure a single phosphorus atom's electron spin in silicon, advancing scalable quantum processor development.

Findings

Achieved single-shot readout of a phosphorus donor electron spin

Demonstrated Rabi oscillations via electron spin resonance

Observed spin coherence time exceeding 200 microseconds

Abstract

A single atom is the prototypical quantum system, and a natural candidate for a quantum bit - the elementary unit of a quantum computer. Atoms have been successfully used to store and process quantum information in electromagnetic traps, as well as in diamond through the use of the NV-center point defect. Solid state electrical devices possess great potential to scale up such demonstrations from few-qubit control to larger scale quantum processors. In this direction, coherent control of spin qubits has been achieved in lithographically-defined double quantum dots in both GaAs and Si. However, it is a formidable challenge to combine the electrical measurement capabilities of engineered nanostructures with the benefits inherent to atomic spin qubits. Here we demonstrate the coherent manipulation of an individual electron spin qubit bound to a phosphorus donor atom in natural silicon, measured electrically via single-shot readout. We use electron spin resonance to drive Rabi oscillations, while a Hahn echo pulse sequence reveals a spin coherence time (T2) exceeding 200 \mu s. This figure is expected to become even longer in isotopically enriched 28Si samples. Together with the use of a device architecture that is compatible with modern integrated circuit technology, these results indicate that the electron spin of a single phosphorus atom in silicon is an excellent platform on which to build a scalable quantum computer.