Entangling dopant nuclear spins using double quantum dots

Lead Research Organisation: University of Cambridge
Department Name: Physics


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.
Description We have developed ways in which to measure the quantum state of electrical devices in silicon, by using radio frequency techniques.
Exploitation Route We are working to further develop measurement technology for silicon quantum computers.
Sectors Electronics

Description Consolidator grant
Amount € 2,400,000 (EUR)
Organisation European Research Council (ERC) 
Sector Public
Country Belgium
Start 05/2015 
End 05/2020
Description Programme grant
Amount £2,715,071 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 01/2016 
End 12/2020
Description Winton
Amount £50,000 (GBP)
Organisation University of Cambridge 
Sector Academic/University
Country United Kingdom
Start 09/2015 
End 09/2017
Description Hitachi Cambridge Laboratory 
Organisation Hitachi Cambridge Laboratory
Country United Kingdom 
Sector Private 
PI Contribution I provided the use of equipment and staff time.
Collaborator Contribution They provided the use of complementary equipment and staff time and material.
Impact All papers reported are written jointly with members of HCL.
Start Year 2007
Description Spintronics measurements with University of Leeds 
Organisation University of Leeds
Department School of Physics and Astronomy
Country United Kingdom 
Sector Academic/University 
PI Contribution I have hosted 3 students from the University of Leeds, each for more than 2 weeks. During this time they performed measurements using my systems.
Collaborator Contribution They provided materials.
Impact It has strengthened the collaboration between the groups.
Start Year 2014
Description General audience lecture in Cambridge 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Professional Practitioners
Results and Impact As part of the Clare College 'Great books series', I presented a general audience talk about 'The Feynman Lectures in Physics'. This explained the background and strengths of these books and why they have had a big impact on physics. I believe that this lecture was successful in explaining what makes physicists tick to academics in other disciplines, predominantly in the humanities.
Year(s) Of Engagement Activity 2016
Description Stall at Maker Faire Rome 2015 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Together with colleagues at Hitachi Cambridge Laboratory I developed and ran a stall titled 'Microcontrollers in an adventure with science!' at Maker Faire Rome. This involved preparing a set of experiments and performing them with members of the public over three days. The event was attended by over 100,000 people and we estimate that we interacted directly with more than 1000. We aimed to spark interest in science and believe that we were highly successful in accomplishing this.
Year(s) Of Engagement Activity 2015
URL http://www.makerfairerome.eu/en/