Silicon-based Integrated Single-Spin Quantum Information Technology

Lead Research Organisation: University of Southampton
Department Name: Electronics and Computer Science


The aim of this project is to realize a world-first Si-based integrated single-spin quantum bit (qubit) system on ultrathin silicon-on-insulator (SOI). We develop a precisely-controlled single-electron transfer technique to initialize truly single-electron spin (single-spin) states, micro electron spin resonance (micro-ESR) for single-spin manipulation, and a 'spin-to-charge' conversion technique for readout. These challenging technical requirements will be met by synergistically combining the expertise of the University of Southampton on cutting-edge silicon-based nanofabrication and single-electron devices, the University of Cambridge and the Hitachi Cambridge Laboratory on solid-state qubits and the associated low-temperature & RF measurements, and the NTT Basic Research Laboratories on single-electron / spin control technology.The first Si-based qubit was proposed by Kane using nuclear spins of phosphorous donor atoms in Si (Si:P qubits). This proposal attracted much interest due to the very long decoherence time of nuclear spins in Si. However, challenging bottom-up nanotechnologies, e.g. STM lithography, are required to control the number and position of P atoms embedded in silicon relative to surface control gates. Rather than using donors, which are atomic-like species, it is also possible to confine electrons in nano-fabricated structures known as quantum dots (QDs). An exquisite degree of control over single-electron spins (single-spins) has been demonstrated in QDs made from gallium arsenide. Unfortunately gallium arsenide is a nuclear spin rich environment leading to a rapid loss of coherence from electron spins. Recently, QDs capable of confining few electrons have also become feasible in silicon based materials, which have a low nuclear spin density, therefore providing a motivation for this research proposal. The recent appearance of isotopically pure Si materials (28Si 99.9%) also works in favour of Si-based systems by further increasing spin decoherence time. In order to develop the Si-based integrated single-spin qubit system, which has never been achieved, we fully exploit the unique set of state-of-the-art nanotechnologies brought together in our project team. Firstly, single-electron turnstile technology is adopted in order to prepare the well-defined initial single-spin states. Secondly, a high-speed charge detection technique is introduced using the radio-frequency single-electron-transistor (RF-SET). Thirdly, the detection of a single-spin state is realized based on the spin-to-charge conversion method. We propose a revolutionary SOI-based technology platform for integrated single-spin qubits, which features double single-spin turnstile devices (SSTDs) built as two parallel SOI-nanowires (SOINWs) with their edges interconnected by another short SOINW. The SSTDs are co-integrated with three other key components: (1) an in-plane single-electron electrometer formed adjacent to the edge of one of the SSTDs, (2) a micro-ESR device formed by using a metallic waveguide and placed near the SOINW interconnect, and (3) a nanomagnet which generates a magnetic field gradient across the single-spin qubits. By integrating all the building-blocks in a nanoscale footprint, we fully investigate initialization, selective manipulation and readout of the single-spin qubits for the first time on Si.


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Gonzalez-Zalba M (2011) A hybrid double-dot in silicon

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Fernando Gonzalez-Zalba M (2012) A hybrid double-dot in silicon in New Journal of Physics

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Gonzalez-Zalba M (2013) A hybrid double-dot in silicon

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Gonzalez-Zalba MF (2014) An exchange-coupled donor molecule in silicon. in Nano letters

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Lambert NJ (2014) A charge parity ammeter. in Nano letters

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Betz A (2014) Ambipolar quantum dots in intrinsic silicon in Applied Physics Letters

Description Highly tuneable and high density lithographically defined Si multiple quantum dots were fabricated for the first time in parallel via a scalable VLSI compatible fabrication process for the realisation of single electron qubits for quantum computing. Beneficiaries: Scientists, engineers and manufacturers working on nanospintronics and spin-based QIP as well as the ICT business giants such as IBM, HP, TI, Hitachi and Sumsung who have already made an enormous R&D investment in this area.
First Year Of Impact 2014
Sector Digital/Communication/Information Technologies (including Software),Electronics
Impact Types Cultural


Description Silicon-based Integrated Single-Spin Quantum Information Technology 
Organisation Hitachi Cambridge Laboratory
Country United Kingdom 
Sector Private 
PI Contribution Design, analysis and fabrication
Start Year 2010
Description Silicon-based Integrated Single-Spin Quantum Information Technology 
Organisation NTT Basic Research Laboratories
Country Japan 
Sector Public 
PI Contribution Design, analysis and fabrication
Start Year 2010
Description In a spin over IT revolution - Southampton Uni Scientists aim for 'quantum leap in computer technology 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Primary Audience
Results and Impact Newspaper Article in Hampshire Chronicle.
Year(s) Of Engagement Activity 2010