Nuclear Nanomagnets for Quantum Optical Spin Devices
Lead Research Organisation:
University of Bristol
Department Name: Physics
Abstract
Nuclear Nanomagnets for Quantum ComputingInformation technology today involves manipulating and transporting small collections of charges through a system of small wires and semiconductor transistors. Making faster and cheaper computers means making these components smaller - in fact their size is halving every two years, and soon we will reach the limit where transistors are the same size as the atoms themselves! Electrons can be thought of as being like a particle or like a wave, and it is the size of the electron wave that determines its behaviour in such small components. Quantum mechanics, the physics that describes such small systems, predicts that electrons in such small components will have totally different properties, and we will have to design our components in a completely new way.Understanding how to deal with the quantum behaviour of electrons presents us with the opportunity to make a new type of computer. Researchers have shown that a quantum computer is theoretically possible by making use of the purely quantum nature of electrons and light. These quantum computers are still in their very early stages, but one day they will perform calculations that will never be possible with conventional computers. My intended research will involve investigating a new type of architecture for a quantum computer. In a quantum computer, information must be stored and transmitted in a reliable way. I will show that it is possible to store information by putting a single electron into a quantum dot . This is a type of nanoscale semiconductor that can store a single electron, and prevent it from interacting or colliding with other electrons and losing its information. It turns out that the best way to store information in the electron is to encode it into its spin . Spin is the intrinsic magnet of an electron. We can change its direction from up to down , in the same way that bits in a computer have the value 0 or 1 .Electron spin is a very good way to store information in quantum dots, but in fact we cannot store the electron spin forever. The problem is that the electron sits inside a semiconductor, which consists of a lattice of atomic nuclei. Each of these nuclei also has its own intrinsic spin, which the electron feels. The magnetic field from each nucleus is very weak, but eventually the electron spin will change due to these nuclei. In my work, on the other hand, I am going to make use of the nuclei. Generally, the nuclear spins point in all directions, but it is also possible to use the electron to redirect all the nuclei to point in the same direction. There are about 10000 nuclei inside our quantum dot, so aligning them all means that the magnetic field felt by the electron is now very large. The nuclei now have a positive effect on the electron spin. Everything is aligned in the same direction and the electron spin may be stored for extremely long times.Solving the problem of how to store electron spins is no good, however, if we are not able to read out and transport its state to another electron spin to perform a calculation. Fortunately, electrons in quantum dots are able to absorb and emit light, and when they do this they also give the information about their spin to a single photon (a particle of light) which we are able to detect. The only problem is that waiting for the electron to produce a photon takes a long time. To make electrons absorb and emit photons faster, we put them into photonic structures that control how the photons interact with the electrons. In my work I will design photonic structures and techniques that are not only so effective that I will be able to either make a very strong nanomagnet, but also so sensitive that I will detect just a single nucleus. This work will help us to understand not only how to make quantum computers using semiconductors, but will tell us a great deal about how to make these basic interactions work in other systems as well.
People |
ORCID iD |
Ruth Oulton (Principal Investigator) |
Publications
Zou L
(2014)
Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies
in Applied Physics Letters
Young AB
(2015)
Polarization Engineering in Photonic Crystal Waveguides for Spin-Photon Entanglers.
in Physical review letters
Young A
(2011)
Quantum-dot-induced phase shift in a pillar microcavity
in Physical Review A
Thijssen A
(2012)
Transfer of arbitrary quantum emitter states to near-field photon superpositions in nanocavities
in Optics Express
Luxmoore IJ
(2013)
Interfacing spins in an InGaAs quantum dot to a semiconductor waveguide circuit using emitted photons.
in Physical review letters
Luxmoore I
(2013)
Optical control of the emission direction of a quantum dot
in Applied Physics Letters
Lopez-Garcia M
(2014)
Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation
in Applied Physics Letters
Lopez-Garcia M
(2018)
Light-induced dynamic structural color by intracellular 3D photonic crystals in brown algae.
in Science advances
Lang B
(2016)
Time-reversal constraint limits unidirectional photon emission in slow-light photonic crystals.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Description | Our investigation of transfer of the full phase information in polarization using a variety of nanophotonic structures has lead to novel insights into the behaviour of quantum emitters placed in nanophotonic structures. Until now, angular momentum transfer from a quantum emitter into a nanophotonic cavity or waveguide has been almost entirely uninvestigated. We have investigated a range of waveguide and cavity structures and show unusual circular polarization filtering behaviour. It was initially expected in this proposal that the cavity could be analysed to determine how it couples polarization. However, we now reveal that one must consider the nanophotonic structure and the the exact quantum dot position as a whole. In investigating schemes to read out single nuclear spins in quantum dots, I have developed the ideas further. By collaborating with experts in Bristol on quantum information, we have identified a means of entangling a photon with a nuclear spin indirectly. This idea has lead to the funding of FP7 project SPANGL4Q. Finally, with our growing understanding of how polarization behaves in nanostructures, I have established a collaboration with biologists at Bristol Univeristy, where we are investigating the polarization dependent reflection of light in plant leaves and insect eyes, funded by an EPSRC follow up grant. |
Exploitation Route | Understanding of how emitters that interact with circular polarization of light will have applications not only in quantum circuits, but we are also investigating whether a nanophotonic cavity or nanoantenna may be used to detect chiral molecules. The difference between left and right handed molecules causes huge differences in biology: their detection may lead to a means of sorting them. |
Sectors | Aerospace/ Defence and Marine Digital/Communication/Information Technologies (including Software) Electronics Manufacturing/ including Industrial Biotechology Pharmaceuticals and Medical Biotechnology |
URL | http://www.bristol.ac.uk/physics/people/205598/index.html |
Description | Biomimetics for Quantum Optics |
Amount | £297,434 (GBP) |
Funding ID | 121817 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 03/2012 |
End | 03/2014 |
Description | EPSRC Standard Grant |
Amount | £842,457 (GBP) |
Funding ID | EP/M024156/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 06/2015 |
End | 06/2018 |
Description | FP7 FET-Open project SPANGL4Q |
Amount | £2,160,000 (GBP) |
Funding ID | SPANGL4Q 284743 |
Organisation | European Commission |
Sector | Public |
Country | European Union (EU) |
Start | 03/2012 |
End | 08/2015 |
Description | Solid State Quantum Networks |
Amount | £1,000,000 (GBP) |
Funding ID | EP/J007994/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 08/2011 |
End | 12/2014 |
Description | COST |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Policymakers/politicians |
Results and Impact | As a result of my activities in quantum technologies I was asked to be UK representative on COST Action "Nanoscale Quantum Optics". Here I became gender balance advisor and tackled questions regarding under representation of women in the quantum technology area. I gave information sessions about implicit bias and other issues at scientific meetings, to the general audience of all attendees - men and women scientists. I also ran discussion sessions and ran two surveys to monitor attitudes towards gender imbalance to monitor changes in opinion. The survey showed that after the intervention many more men reported being engaged in activities to counteract underrepresentation of women in science. The outcome was that I was asked to present at Europe's foremost science policy conference, ESOF 2018. I was also asked to present in Feb 2020 to policy makers in Brussels (from COST and from Horizon 2020) about the activities I had undertaken. |
Year(s) Of Engagement Activity | 2016,2017,2018,2019 |
URL | https://www.cost-nqo.eu/gender-balance/ |
Description | Interview for Observer Tech Monthly Suppliment |
Form Of Engagement Activity | A magazine, newsletter or online publication |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | Lively discussion in the Views section at end of online article. After publication several of my colleagues and friends had said that they had seen the article. |
Year(s) Of Engagement Activity | 2014 |
URL | http://www.theguardian.com/science/2014/mar/06/quantum-computing-explained-particle-mechanics |
Description | Invited Speaker and Panel Member at Royal Society Frontier of Science Meeting |
Form Of Engagement Activity | A formal working group, expert panel or dialogue |
Part Of Official Scheme? | Yes |
Geographic Reach | International |
Primary Audience | Other academic audiences (collaborators, peers etc.) |
Results and Impact | I was recently invited to talk and act as an expert panel member on the topics of "quantum communications" at the Royal Society UK-Russia Frontiers of Science Meeting in Kazan, Russia. The scope of the conference was to examine chosen topics of science at the "frontier", of which quantum information was one. The invitees were a broad range of speakers, with a 40 minute panel question and answer session to discuss the broader aspects of the research. The event was covered in the local paper. I was also invited to visit the Kazan University Physics Dept. |
Year(s) Of Engagement Activity | 2013 |
Description | Invited Speaker at Royal Society 150 year celebration of Maxwell's paper |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Professional Practitioners |
Results and Impact | Invited presentation on photonic crystals for the Royal Society's 150th anniversary celebration of Maxwell's seminal paper |
Year(s) Of Engagement Activity | 2015 |
Description | NSQI Evening Public Talk "Crazy-Quasi Particles for Storing Quantum Light" (2014) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Public/other audiences |
Results and Impact | Audience was booked out and several people came to speak to me afterwards, including a 15 year old that was interested in quantum cryptorgraphy. My slides were requested after the talk by member of the public so these were put online. |
Year(s) Of Engagement Activity | 2014 |