Entangling dopant nuclear spins using double quantum dots

Lead Research Organisation: University College London
Department Name: London Centre for Nanotechnology

Abstract

Quantum mechanics has led to a deep and profound understanding of the electronic and optical properties materials, which has underpinned the technological revolution of the past century. Yet, there are key elements of quantum mechanics, specifically ideas such as 'coherent superposition' and 'entanglement', which have still to be harnessed directly in a technological application. With our improving ability to control smaller and smaller devices, with ever greater precision, we begin to enter a regime where such concepts can evolve from abstract 'thought experiments' to phenemona exhibited by real devices. Sufficiently controlled, superposition and entanglement will enable a new set of technologies - termed Quantum Technologies (QTs)- which offer major and fundamental improvements over certain existing technologies. Examples include ultimately secure communication, enhanced sensors, and 'quantum' computers able to solve problems that are simply intractable on any existing computer today.

Silicon devices have demonstrated quantum bit (qubit) characteristics which make them extremely promising for future QTs. As for most potential QT platforms, the next key step is identifying ways to scale up control and interactions between qubits, and, as seen when comparing different QT approaches, there is a compromise between using 'natural' quantum systems such as those based on atoms, and 'artificial' ones such as those based on superconducting circuits or quantum dots.

This project will bring together both such approaches, as is possible within a silicon-based architecture, in order to benefit from their respective advantages. We will use the uniquely long coherence times of donor spins in silicon (which can be as long as hours), with the tunable control of quantum dots in which entangled singlet and triplets are natural basis states. In doing so, we will demonstrate a scalable method to entangle very long-lived quantum bits in silicon, which will enable future applications in metrology and quantum computers.

Planned Impact

This project seeks to explore a new idea with the potential to dramatically impact progress towards silicon-based quantum technologies.

Although quantum physics is now over a hundred years old, some of the strangest and most profound outcomes of quantum physics (such as superposition, or entanglement) have yet to be directly exploited in a technology. Such technologies are termed quantum technologies, and we are still learning about the tremendous enhancements they might offer over existing technologies. These include computers ('quantum computers') with the capability of solving problems which are simply intractable on the fastest computers today. The societal impact of such a computational power can not easily be overstated; the full potential is as unforeseeable today as preliminary computers were many decades ago. However, some applications have already been identified, such as quantum simulators, capable of modelling and predicting material, chemical and biochemical properties far more accurately than can be conceived today.
Other identified types of quantum technologies include enhanced sensors and imaging devices, as well as highly secure encrypted data transmission with impacts in individual and industrial data privacy.

In the United State Federal Vision for Quantum Information Science, published in 2009, the following is written about the potential for quantum technologies: "[They] are at an early pre-application stage, but possess a novelty and a richness that suggests the likelihood of even greater unanticipated impact [than the transistor or laser]". It is therefore no surprise that major ICT companies around the world are investing heavily in research into quantum technologies - these companies include Hitachi (our industrial project partner on this proposal) IBM, Hewlett-Packard, Fujitsu, Siemens, Microsoft, Toshiba, Nokia and NTT.

One of the key challenges that must be addressed in advancing progress towards practical quantum technologies is scaling up small demonstrations of coherent quantum control to many-body systems. Meeting this challenge in any material would be a major achievement, but to do so in silicon (as we propose in this project) would be especially exciting, as it the most important material used in today's technologies. This would enable quantum technologies to harness the mature silicon nano-fabrication techniques developed over the past decades, and would permit the integration of quantum and 'classical' forms of information processing on the same chip.

Aside from the main objective of this project to develop quantum technologies, our basic research on dopants in silicon nanodevices may also lead to impact in conventional silicon-based technologies, especially 'beyond CMOS' technologies. The size of transistors in current computers processors are approaching the limit where the device performance is affected by the discrete number of dopant atoms in the channel. A more thorough understanding of how to tune and control the interaction of the dopant atom with charge transport in the nanodevice could impact the design of future transistors.

Publications

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Ahmed I (2018) Radio-Frequency Capacitive Gate-Based Sensing in Physical Review Applied

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Atatüre M (2014) Quantum information. A gem of a quantum teleporter. in Science (New York, N.Y.)

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Balian S (2014) Quantum-bath-driven decoherence of mixed spin systems in Physical Review B

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Bienfait A (2016) Controlling spin relaxation with a cavity. in Nature

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Bienfait A (2017) Magnetic Resonance with Squeezed Microwaves in Physical Review X

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Lo C (2014) Silicon's second act in IEEE Spectrum

 
Description We have demonstrated the coupling of the electron spin of a quantum dot and a single donor atom within a CMOS transistor. This transistor was not fabricated in order to be a quantum device, but if operated at low temperature and under appropriate bias conditions, quantum behaviour can be observed. This important results lays the foundation for developing qubit devices made through advanced CMOS fabrication processes. We have also made a discovery on the effects of strain on donor spins in silicon - an effect orders of magnitude greater than previously thought. Strain is ubiquitous in silicon nano-devices, and so this discovery is crucial if donor spins are to be used in future technologies such as quantum computers, quantum memories, or in spintronics. Finally, we have made major improvements in the sensitivity with which silicon quantum dots can be measured in silicon nano-devices using gate reflectometry, rather than a separate sensor device, obtaining world-leading sensitivity in this technique, which will be a key part in scaling up architectures for silicon-based quantum processors.
Exploitation Route These findings provide motivation to harness the capabilities of advanced CMOS fabrication processes to make quantum devices, including qubits. The results have led to a major €10M proposal under the EU Quantum Technologies Flagship with numerous partners around Europe, focused on developing a silicon-based quantum processor.
Sectors Digital/Communication/Information Technologies (including Software),Electronics

 
Description Our results on the COUPLING OF QUANTUM DOTS AND SINGLE DOPANT AOTM SPINS in CMOS transistors have stimulated a new collaboration with IMEC (Leuven, Belgium), as well as helped secure new H2020 funding with partners from 5 EU countries. It has also secured two co-funded PhD studentship with 50% support from Hitachi Cambridge Laboratory. Each of these projects are focused around harnessing existing capabilities in advanced CMOS fabrication for the purposes of developing qubit devices. Overall, such activities enhance the UK's standing as a leader in the design and measurement of silicon devices for quantum technologies, working with advanced fabrication facilities in the rest of Europe. Our results on STRAIN EFFECTS ON SILICON DONOR SPINS IN NANODEVICES has wide reaching impact in the large international community working on the incorporation of donors spins in nanodevices and their use as qubits, including work on coupling superconducting resonators to spins. Such results are being exploited in both academic and commercial spheres.
Sector Digital/Communication/Information Technologies (including Software),Electronics
Impact Types Economic

 
Description EU Quantum Technology Initiative - Towards a Quantum Technology 'Flagship'
Geographic Reach Europe 
Policy Influence Type Participation in a national consultation
 
Description Evidence to HoC S&T Committee in 2018
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
 
Description On Strategic Research Agenda Workshop Group for QT Flagship
Geographic Reach Europe 
Policy Influence Type Participation in a advisory committee
 
Description UK Quantum Technology Initiative
Geographic Reach National 
Policy Influence Type Participation in a national consultation
Impact Raise the profile of quantum technology and helped bring about a national UK initiative in quantum technology, with (amongst other things) focus on training a skilled workforce in quantum information. There is also the potential for UK economic impact further down the line.
 
Description CDT (Delivering Quantum Technologies)
Amount £5,410,603 (GBP)
Funding ID EP/L015242/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2014 
End 09/2022
 
Description EPSRC Quantum Technology Capital
Amount £8,548,795 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2016 
End 03/2019
 
Description ERC Consolidator Grant
Amount € 2,264,167 (EUR)
Funding ID LOQO-MOTIONS 
Organisation European Research Council (ERC) 
Sector Public
Country European Union (EU)
Start 02/2018 
End 01/2023
 
Description ERC Starter Grant
Amount € 1,875,550 (EUR)
Funding ID ASCENT 
Organisation European Research Council (ERC) 
Sector Public
Country European Union (EU)
Start 12/2011 
End 11/2016
 
Description H2020-ICT-2015
Amount € 460,000 (EUR)
Organisation European Commission 
Department Horizon 2020
Sector Public
Country European Union (EU)
Start 04/2016 
End 03/2019
 
Description Marie Curie Fellowship (Jarryd Pla)
Amount € 144,044 (EUR)
Funding ID QURAM 
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start 03/2014 
End 02/2016
 
Description QT Skills Hub
Amount £3,597,372 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2016 
End 03/2021
 
Description Royal Society Research Grant
Amount £50,000 (GBP)
Funding ID RG090440 
Organisation The Royal Society 
Sector Academic/University
Country United Kingdom
Start 04/2010 
End 03/2012
 
Description Royal Society URF
Amount £496,000 (GBP)
Funding ID UF0763418 
Organisation The Royal Society 
Sector Academic/University
Country United Kingdom
Start 10/2008 
End 09/2013
 
Description Royal Society URF (extension)
Amount £442,388 (GBP)
Funding ID UF120062 
Organisation The Royal Society 
Sector Academic/University
Country United Kingdom
Start 10/2013 
End 09/2016
 
Description CEA Grenoble 
Organisation CEA-Leti
Country France 
Sector Charity/Non Profit 
PI Contribution Measured quantum spin dynamics of finFETs at cryogenic temperatures
Collaborator Contribution Provision of state-of-the-art CMOS finFETs fabricated on a 300mm wafer process
Impact Charge dynamics and spin blockade in a hybrid double quantum dot in silicon M Urdampilleta, A Chatterjee, CC Lo, T Kobayashi, J Mansir, S Barraud, AC Betz, S Rogge, MF Gonzalez-Zalba, JJL Morton Phys Rev X 5 031024 (2015) Directly led to new funding: €4M H2020 grant "MOS-QUITO" commencing 1st April 2016.
Start Year 2015
 
Description Hitachi Cambridge Laboratory 
Organisation Hitachi Cambridge Laboratory
Country United Kingdom 
Sector Private 
PI Contribution We have brought our expertise in the coherent control of spins, including spins in silicon, and in the optical measurement of spins using donor-bound exciton transitions
Collaborator Contribution Hitachi Cambridge Lab are co-funding a PhD student working on silicon quantum devices, and have provided access to millikelvin measurement facilities to researchers in my group, as well as training in the development of RF-reflectometry readout of devices.
Impact Charge dynamics and spin blockade in a hybrid double quantum dot in silicon M Urdampilleta, A Chatterjee, CC Lo, T Kobayashi, J Mansir, S Barraud, AC Betz, S Rogge, MF Gonzalez-Zalba, JJL Morton Phys Rev X 5 031024 (2015) Hybrid optical-electrical detection of donor electron spins with bound excitons in Si CC Lo, M Urdampilleta, P Ross, MF Gonzalez-Zalba, J Mansir, SA Lyon, MLW Thewalt, JJL Morton Nature Materials 14 490 (2015)
Start Year 2015
 
Description Hitachi Cambridge Laboratory / Fernando Gonzalez-Zalba 
Organisation Hitachi Cambridge Laboratory
Country United Kingdom 
Sector Private 
PI Contribution Bringing expertise in silicon spin qubits and quantum information; Measurement infrastructure at UCL for measuring silicon quantum devices and spin qubits and mK temperatures
Collaborator Contribution Co-funding 2 PhD students; Co-supervising both students; Presenting talks to my research group and UCLQ more widely giving industrial perspective; hosting students in Hitachi Cambridge Lab for extended research visits (6-10 weeks) with access to milliKelvin measurement facilities
Impact EU funding proposals: 1) MOS-QUITO project (€3M, awarded April 2016); 2) QT Flagship proposal (€10M, under review)
Start Year 2015
 
Description IMEC 
Organisation Interuniversity Micro-Electronics Centre
Country Belgium 
Sector Multiple 
PI Contribution We have brought our expertise in the design and measurement of silicon quantum devices
Collaborator Contribution IMEC are providing cutting-edge CMOS devices with high-yield, high-purity and small feature sizes. The aim is to jointly develop CMOS-based quantum devices for implementing spin qubits in silicon.
Impact EU funding proposals: QT Flagship proposal (€10M, under review)
Start Year 2016
 
Description Mike Thewalt, Simon Fraser Unversity 
Organisation Simon Fraser University
Country Canada 
Sector Academic/University 
PI Contribution Expertise in pulsed magnetic resonance, quantum information, spin decoherence and dynamical decoupling
Collaborator Contribution Expertise in optical spectroscopy of donors, including donor bound excitons, and access to highly enriched 28-silicon material
Impact 15 joint publications since 2010, including two in Science, one in Nature, four in Nature-family journals and two in Phys Rev Lett.
Start Year 2010
 
Description NPL 
Organisation NPL Ltd
PI Contribution Bringing expertise in silicon spin qubits and quantum information; Measurement infrastructure at UCL for measuring silicon quantum devices and spin qubits and mK temperatures
Collaborator Contribution Co-funding a PhD student; Co-supervising student; Presenting talks to UCLQ more widely giving industrial perspective; hosting student at NPL Lab for extended research visits (6-10 weeks) with access to milliKelvin measurement facilities
Impact N/A
Start Year 2017
 
Description NPL 
Organisation National Physical Laboratory
Department Time, Quantum and Electromagnetics Division
Country United Kingdom 
Sector Public 
PI Contribution We have brought our expertise in highly coherent spins in silicon and rare-earth spins in YSO, including spin coherence times and decoherence mechanisms, as well as expertise in NbN resonator fabrication.
Collaborator Contribution The NPL team have cutting-edge facilities for the measurement of superconducting resonators at mK temperatures, as well as expertise in the design of such structures and coupling them to implanted spins. They are co-funding a PhD student in my group and providing access to specialised measurement infrastructure.
Impact N/A
Start Year 2016
 
Description Patrice Bertet, CEA Saclay 
Organisation Saclay Nuclear Research Centre
Country France 
Sector Public 
PI Contribution Expertise in donor spins in silicon, specifically bismuth-doped silicon. Jarryd Pla, a post-doctoral fellow in the group, has made regular visits to Saclay to fabricate structures and perform measurements.
Collaborator Contribution Expertise in circuit quantum electrodynamics using superconducting resonators and superconducting qubits.
Impact Controlling spin relaxation with a cavity A Bienfait, JJ Pla, Y Kubo, X Zhou, M Stern, CC Lo, CD Weis, T Schenkel, D Vion, D Esteve, JJL Morton and P Bertet, Nature 531, 74 (2016) Reaching the quantum limit of sensitivity in electron spin resonance A Bienfait, JJ Pla, Y Kubo, M Stern, X Zhou, CC Lo, CD Weis, T Schenkel, MLW Thewalt, D Vion, D Esteve, B Julsgaard, K Moelmer, JJL Morton and P Bertet, Nature Nanotechnology 11, 253 (2015)
Start Year 2013
 
Description Ren Bau Liu (Hong Kong) 
Organisation Chinese University of Hong Kong
Country Hong Kong 
Sector Academic/University 
PI Contribution Expertise in experimental measurements of spin decoherence of donors in silicon
Collaborator Contribution Expertise in the theory of open quantum systems, and coupling to spin baths
Impact Uncovering many-body correlations in nanoscale nuclear spin baths by central spin decoherence, W-L Ma, G Wolfowicz, N Zhao, S-S Li, JJL Morton, R-B Liu Nature Communications 5 4822 (2014) Classical nature of nuclear spin noise near clock transitions of Bi donors in Si W-L Ma, G Wolfowicz, S-S Li, J J L Morton, R-B Liu Phys Rev B 92 161403(R) (2015)
Start Year 2013
 
Description Thomas Schenkel, Lawrence Berkeley National Laboratory 
Organisation Lawrence Berkeley National Laboratory
Country United States 
Sector Public 
PI Contribution Expertise in pulsed electron spin resonance, in particular of donors in silicon
Collaborator Contribution Expertise in ion implantation, in particular bismuth donors
Impact 8 joint publications since 2008, including 2 in Nature, 2 in Nature family and 1 in Physical Review Letters: Solid state quantum memory using the 31P nuclear spin JJL Morton, AM Tyryshkin, RM Brown, S Shankar, BW Lovett, A Ardavan, T Schenkel, EE Haller, JW Ager and SA Lyon, Nature 455 1085 (2008) Electrically detected magnetic resonance in a W-band microwave cavity V Lang, CC Lo, RE George, SA Lyon, J Bokor, T Schenkel, A Ardavan and JJL Morton Rev Sci Instrum 82 034704 (2011) Electrically detected magnetic resonance of neutral donors interacting with a two-dimensional electron gas CC Lo, V Lang, RE George, JJL Morton, AM Tyryshkin, SA Lyon, J Bokor, T Schenkel Phys Rev Lett 106 207601 (2011) Electron spin coherence exceeding seconds in high purity silicon AM Tyryshkin, S Tojo, JJL Morton, H Riemann, NV Abrosimov, P Becker, H-J Pohl, T Schenkel, MLW Thewalt, KM Itoh, SA Lyon Nature Materials 11 143 (2012) Electrical activation and ESR measurements of implanted bismuth in isotopically enriched silicon-28 CD Weis, CC Lo, V Lang, AM Tyryshkin, RE George, KM Yu, J Bokor, SA Lyon, JJL Morton, T Schenkel Appl Phys Lett 100 172104 (2012) Stark shift and field ionization of arsenic donors in 28Si-SOI structures CC Lo, S Simmons, R Lo Nardo, CD Weis, AM Tyryshkin, SA Lyon, J Bokor, T Schenkel, JJL Morton App Phys Lett 104 193502 (2014) Reaching the quantum limit of sensitivity in electron spin resonance A Bienfait, JJ Pla, Y Kubo, M Stern, X Zhou, CC Lo, CD Weis, T Schenkel, MLW Thewalt, D Vion, D Esteve, B Julsgaard, K Moelmer, JJL Morton and P Bertet Nature Nanotechnology (2016) Controlling spin relaxation with a cavity A Bienfait, JJ Pla, Y Kubo, X Zhou, M Stern, CC Lo, CD Weis, T Schenkel, D Vion, D Esteve, JJL Morton and P Bertet Nature (2016)
Start Year 2008
 
Title Surface code quantum computer architecture using shuttling spins 
Description Architecture for a fault-tolerant quantum computer based on donor spins in silicon 
IP Reference WO2015124950 
Protection Patent granted
Year Protection Granted 2015
Licensed Yes
Impact N/A
 
Company Name Q & I Ltd 
Description Quantum technology consultancy 
Year Established 2015 
Impact N/A
Website http://www.qandi.co.uk
 
Company Name Quantum Motion Technologies Ltd 
Description The company aims to develop quantum computer architectures based on silicon technology, leveraging CMOS processing to achieve high-density qubits which can scale up to large numbers and tackle practical quantum computing problems. 
Year Established 2017 
Impact N/A
 
Description BBC World Service 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interview on quantum mechanical effects in a likely mechanisms for how birds 'see' magnetic fields.

BBC have been in touch for further information on how this field has developed as it is an area which attracted considerable interest from the public.
Year(s) Of Engagement Activity 2013
 
Description FT Article Oct 2018 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact I was interviewed for and featured in a Financial Times article on Quantum Computing (Oct 2018)
Year(s) Of Engagement Activity 2018
 
Description HoC S&T SelectCommittee June2018 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact - Provided written evidence for the House of Commons Science and Technology Select Committee into Quantum Technologies (April 2018)
- Invited to provide oral evidence at the House of Commons for the Science and Technology Select Committee into Quantum Technologies (June 2018)
- Key recommendations on innovation centres and training taken forward in Science and Technology Select Committee report
Year(s) Of Engagement Activity 2018
 
Description IEEE Spectrum Article 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Overview article on silicon-based quantum computing aimed at wide electronics engineering community. IEEE Spectrum has a circulation of over 380,000 engineers worldwide.

After this was published, companies such as BT made contact to explore potential collaborations
Year(s) Of Engagement Activity 2014
 
Description Inv Talk - 2016 - CWTEC 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Invited presentation entitled "What is a universal quantum computer and how do I build one" delivered at the CW-TEC (Cambridge Wireless Technology) 2016 event. This event is addressed primarily at industry and academia in the sectors of wireless communication, and led to discussions on the likely timescales of commercial quantum computers.
Year(s) Of Engagement Activity 2016
 
Description NPR Interview 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interview on National Public Radio (NPR), USA on "Spintronics: A New Way To Store Digital Data".

Active discussed thread on NPR website for this radio programme discussing future technologies
Year(s) Of Engagement Activity 2010
 
Description Physics Teacher Training 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact 15 teachers of Physics at A/AS-level attended a talk I had prepared on how to present some of the latest developments in measurements of quantum dots and development of a new current standard in terms of A-level physics, providing ideas for how they can cover this recent work in their classrooms.
Year(s) Of Engagement Activity 2016
 
Description Quantum Engineering workshop Nov 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Organiser and chair of "Engineering Needs and Challenges in Quantum Technology" workshop, London, November 2018. New type of workshop focused specifically on identifying joint engineering needs across quantum technology.
Year(s) Of Engagement Activity 2017
 
Description Quantum of Spin 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Quantum of Spin was an exhibit on our research on using spins for quantum technologies, reaching over 10,000 members of the public. The hand's on exhibits including a real MRI system for which they were able to make and image "phantoms", resonant experiments and illustrations of superposition and entanglement.

HRH The Duke of York developed an interested in quantum technologies following a discussion at this exhibit, which led to two meetings at Buckingham Palace on Quantum Technologies
Year(s) Of Engagement Activity 2012
 
Description School visit (Osaka high school) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact Talk to Japanese high-school students on introduction to quantum computing

It was clear this was a very different style of teaching than the students were used to, but they seemed to enjoy the challenging ideas
Year(s) Of Engagement Activity 2010
 
Description School visit (St Pauls Girls School) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Talk on weirdness of quantum mechanics and applications in technologies

Students requested internships in my lab
Year(s) Of Engagement Activity 2013