Building Large Quantum States out of Light

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

We aim to build the world's biggest quantum photonic network, in which up to twenty photons, elementary particles of light, are connected to produce a large, controllable quantum system. This new tool will open up important realms of physics that have been too complex to study conventionally, such as biological energy transport and high-temperature superconductivity. Since photons are used to transport information, the network will also form a platform for revolutionary new quantum technologies like ultra-precise sensing and guaranteed-secure communication across the globe. To achieve such a large quantum system, we will introduce new techniques that fundamentally change the scalability of photonics. This will lay the ground for even larger networks in the future, establishing the UK as a leader in the nascent quantum technology industry.

We have known for over a hundred years that atoms and molecules don't move according to Newton's laws. Instead, they obey the laws of quantum mechanics. These laws are strange but they explain how chemical bonds form and why silicon chips can make computers. These insights drove a profound technological revolution in the 20th century, spanning extraordinary advances in medicine, telecoms, and computing. It is now clear that our current knowledge of quantum systems is just the tip of the iceberg. While we can understand quantum effects between just two particles exactly, or between many atoms in an approximate way, as is the case for a semiconductor transistor, large objects composed of many particles cannot be analysed in detail. They are too complicated, and in fact beyond a few atoms, they cannot even be simulated with a supercomputer. The problem is that quantum systems are fuzzy, in a sense, so each particle is a distribution, not a single point. To describe many particles requires distributions of distributions of distributions and so on. This explosion in complexity means that many interesting systems in nature - in biology and medicine, particle physics and materials science - have so far been largely closed to analysis. The only way to study complex quantum systems in detail is to build a machine that can create them in a tailored, controllable way, so that we can build models of the real systems we want to study.

Over the past two decades, a new science of quantum information has developed. In addition to their application to problems in the natural sciences, it has been shown that large controllable quantum systems can underpin a host of transformative new technologies, including the possibility of quantum computers that are exponentially faster than today's best computers. Perhaps surprisingly, one of the most advanced approaches to quantum computation involves photons instead of atoms. Photons can easily be transported by optical fibres, which are a mature technology used for telecoms and the internet, and they experience almost no noise. Because of these advantages, optical quantum cryptography over short distances is already commercially available.

To go further and realise the most ambitious goals of quantum information science, and to open up the investigation of complex quantum systems, many photons must be connected and precisely manipulated. We aim to meet this challenge by leveraging advanced fabrication methods developed for the modern telecoms industry to build a large-scale controllable quantum photonic network, at the level of around twenty photons. In particular, we will use silica integrated optics -- circuits for light written on small glass chips -- to connect photons with minimal losses. These will be joined to superconducting detectors that count photons with high efficiency, and novel quantum memories that can store photons and synchronise the network. Combining quantum memories with these highly efficient technologies will enable the network to operate with at an unprecedented scale, giving access to new physics and new technologies.

Planned Impact

Information is at the heart of modern society. From talking with friends across the world, shopping on to the internet, accessing an ATM, and even using a checkout at the grocery store, information is critical to everyday life.
All current information technologies - communications, sensors, computers, imaging devices - are designed using principles of classical physics. Yet the world is at its core described by quantum physics. The emergence of quantum information science has shown how new design principles for IT based on this theory can deliver radically new and different solutions for information processing: superfast computers, able to break the strongest known secret codes; completely secure communications systems; ultra-precise measurement and imaging. The current project will provide a demonstration of a first generation quantum communications and sensing network.
The project and its outcomes will therefore impact on:

(a) Society, by providing a template for new information technologies to enhance our quality of life by providing powerful new computers and secure data handling

(b)The Economy, by demonstrating a new kind of information processing, that requires new machines. The IT sector is an immensely successful and important part of the UK economy, with turnover in excess of £140bn annually;

(c)Knowledge: both academic and commercial, as the new regimes of physics afforded by the research become accessible for discovery;

(d) People, through the new understanding, technical expertise and skills developed by the researchers during the project, including training in engagement with the media, the public and policy makers.

In addition to academic benefits, the outcomes of the research will be of value to UK and global commerce, the general public and government. This will happen in the following ways:

(i) Commerce: The development of new information technologies has always led to economic impact. From Babbage's Difference Engine, Flowers' Colossus an Mauchly and Eckert's ENIAC grew Apple - the world's largest company. Although those computer pioneers could not foresee this impact, it is fair to argue that the breakthrough in digital computation they instigated has radically transformed the economy.

(ii) The Public: Everyone, whether they live in highly industrialized countries, or in the developing world, is dependent on access to information that is increasingly delivered by new technologies. Radical changes in the technology itself will foment equally radical changes in how it is used. Consider, for instance, how cellular telephony has transformed society in the last 20 years. Similar changes will happen as quantum technologies become embedded. Beyond this, however, the science associated with large-scale quantum states is something that captures the imagination. Schrödinger's Cat is not simply a metaphor in physics, but a re-conceiving of the natural world. This is something for which there is a great appetite.

(iii) Government: The security of society is the responsibility of governments and their agents. This responsibility ranges from the security of patient data in the NHS and national defense to secure communications for the smart grid. Regulation must be informed by the capabilities of current and future technology, so that legislation can be effective. Therefore it is critical to explore the boundaries of what is possible so that what it may, or may not, deliver is evident. For example, the US National Security Agency expects its currently encrypted data to be secure for 20 years. What if a quantum computer that can crack the RSA code appears in 15 years time? How will the security of back data be guaranteed, and what steps should be taken now to ensure this?

Even a quantum network that is in modern terms as nascent as Babbage's and Flowers' clunky mechanical computers will open the way to demonstration of a radical information technology of transformative power.

Publications


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Barbieri M (2015) Qubit-Programmable Operations on Quantum Light Fields. in Scientific reports
Bartley T (2015) Directly comparing entanglement-enhancing non-Gaussian operations in New Journal of Physics
Barz S (2016) Enhanced delegated computing using coherence in Physical Review A
Baumgratz T (2016) Quantum Enhanced Estimation of a Multidimensional Field. in Physical review letters
Blandino R (2015) Heralded noiseless linear amplification and quantum channels in Physical Review A
Boutari J (2016) Large scale quantum walks by means of optical fiber cavities in Journal of Optics
 
Description The project is ongoing.

The goal of this project was to develop both the tools necessary to enter new regimes of complexity in quantum optical experiments and to begin to explore both the physics and applications possible with these larger quantum states of light. We have already made major contributions to both of these areas.

With respect to the development of the experimental tools, we have made progress in key areas, including single photon sources, photonic circuits and single photon detectors:

- We have discovered that the existing fabrication techniques employed at the University of Southampton to manufacture photonic chips provides a unique platform on which many identical single photons can be built. This has enabled us to build an array of 18 highly indistinguishable and pure heralded single photon sources on a single chip
- We have developed, manufactured and characterised a flexible, reconfigurable approach to building low-loss optical circuits on photonic chips and have filed for a patent protecting the new loss-tolerant circuit design that we have invented during the development of these devices
- We have installed high-efficiency photon number resolving detectors, and have developed a new protocol for efficient characterisation suited to this class of detectors.

With respect to the physics and applications of these large quantum states made possible by the development of these tools we have also made good progress:

- We have discovered a set of novel features in the interference of three or more quantum particles and probed these new effects using the heralded photon source array mentioned above. We have further developed new theoretical tools and models to characterise these new multi-photon states
- Development of a new theoretical analysis for time-domain quantum walks along with the construction of a fibre-based setup to implement the design experimentally
- Demonstration of an efficient approach to estimating simultaneously the phase and phase noise imposed on an optical beam.
Exploitation Route Our new modular approach to building low-loss silica photonic chips may have use in the development of new quantum photonic technologies and our design for configuring universal linear optical interferometers is likely to have applications within classical photonics for switching and signal routing.

Our theoretical and experimental work on understanding the subtleties and complexities of multi-photon interference will have important consequences for those research groups involved in Boson Sampling and recent applications of this in quantum chemistry simulations.

We hope our novel multiplexed single photon source design will be able to be developed by many other research groups since it is largely based on commercially available components, reducing the barrier to replicating and improving upon our design.
Sectors Digital/Communication/Information Technologies (including Software),Electronics
URL http://www.bloqs.org/
 
Description NIST 
Organisation National Institutes of Health (NIH)
Department National Institute of Standards & Technology (NIST)
Country United States of America 
Sector Public 
PI Contribution We have undertaken optical modelling and characterization of superconducting photon detectors fabricated at NIST.
Collaborator Contribution NIST has fabricated superconducting photon detectors and advised us on installation and operation.
Impact Joint publications in peer-reviewed journals.
Start Year 2010
 
Description Paderborn 
Organisation University of Paderborn
Country Germany, Federal Republic of 
Sector Academic/University 
PI Contribution Characterization of spontaneous parametric down-conversion in multiple waveguides on a single periodically-poled KTP chip.
Collaborator Contribution Advice concerning development of a heralded photon source built with a waveguide in periodically-poled KTP.
Impact Preliminary studies of photon-pair generation in KTP waveguides at Oxford.
Start Year 2013
 
Description 2015 Royal Horticultural Society Tatton Park Flower Show 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Matthew Posner helped design a show garden which contained many metaphors for how light interacts with the world around us
Year(s) Of Engagement Activity 2015
URL https://www.rhs.org.uk/shows-events/rhs-flower-show-tatton-park/exhibitors/Archive/2015/gardens/Refl...
 
Description 2016 University of Southampton Science and Engineering Day 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Other audiences
Results and Impact Engagement with 256 children and accompanying parents at the 2016 University of Southampton Science and Engineering day with the Lightwave Roadshow, an outreach education program based at the Optoelectronics Research Centre and supported by the EPSRC Future Photonics Manufacturing Hub. Significant participation by postgraduate students with research relevant to the Hub activities, with positive change of attitude and renewed engagement of the program following this activity.
Year(s) Of Engagement Activity 2016
URL http://www.zeplerinstitute.ac.uk/news/4858
 
Description Ask the Scientist (Southampton General Hospital) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact C. Holmes was on the panel at an 'Ask a Scientist' event hosted at Southampton General hospital attended by 40 pupils from years 10 and 11.
Year(s) Of Engagement Activity 2014
 
Description Atomic & Laser Physics / Condensed Matter Physics - Oxford Physics Alumni Garden Party 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact J. Boutari and M.Vidrigin performed outreach experiments with optics and audience participation to the annual "Garden Party & ALP/CMP alumni event"
Year(s) Of Engagement Activity 2015
 
Description BBC Documentary - QUANTUM 
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 There are opportunities for further contributions to documentaries in the future.

Documentary has not been broadcast yet.
Year(s) Of Engagement Activity 2014
URL http://www.bbc.co.uk/programmes/b04v5vjz
 
Description Bringing Science to Life - Thomas Hardye School 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Matthew Posner gave a talk at Thomas Hardyee School as part of the University PE roadshow talking about how photonics can be used to build the computers of the future.
Year(s) Of Engagement Activity 2015
 
Description British Science Festival Invited Talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Matthew Posner gave an invited talk titled 'Light shaping the future'
Year(s) Of Engagement Activity 2015
 
Description Cafe Scientifique Salisbury 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Matthew Posner gave a talk titled 'From heliographs to the Internet: celebrating Light'
Year(s) Of Engagement Activity 2015
URL http://cafescientifiquesalisbury.org.uk/2015/09/light/
 
Description Cheltenham Science Festival 2016 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Over three days, a group of NQIT researchers and graduate students demonstrated the fundamental physics behind our approach to quantum computing - ion traps and photonics - and explained some of its potential applications. We used a rotating saddle trap that keeps a ping pong ball stable while it spins to illustrate how we use a rotating electric field to trap single ions in an ion trap. This was then further demonstrated with a dust trap where electrostatically-charged grains of sand are trapped inside a static electric field.

We showed visitors how you can control light with a beautifully simple demonstration involving shining a laser pointer into a flow of water - the photons follow the curving path of the water in just the same way that they flow down an fibre optic cable providing internet to peoples' homes or photonic networking in our quantum computer.

We explained why quantum computers will be faster than regular computers using a fun and quick game of "snap" with a twist that the 'regular computer' has to sort through the deck of cards one card at a time whereas the 'quantum computer' can see all the cards face-up on the table because they are in a "quantum superposition of all possible solutions".

Lastly, we invited visitors to find the pirate treasure (and win a chocolate coin) by finding the shortest route to search all the locations on the treasure map. This is a demonstration of the Travelling Salesman problem - it's not that difficult to solve for a handful of points on a map, but the complexity increases exponentially as you add more points to the map. This is the sort of problem that quantum computers are likely to be able to solve considerably more quickly than classical computers. Hundreds of visitors to the festival - young and old - visited our stand.
Year(s) Of Engagement Activity 2016
URL http://www.nqit.ox.ac.uk/news/nqit-cheltenham-science-festival
 
Description Copenhagen EuroScience Open Forum 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact S. Barz delivered a talk and podium discussion on "Secure quantum computation".
Year(s) Of Engagement Activity 2014
 
Description How will Quantum Technologies change how you do business? 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Industry/Business
Results and Impact In July 2016, NQIT's KE fund award was used to host an event for local businesses entitled "How will Quantum Technologies change how you do business?". Around 50 people from a range of businesses along with members of the public came to the evening session at the Oxford Martin School, which is an interdisciplinary research centre. The attendees were given talks about business opportunities, an introduction to current research, and responsible research and innovation (RRI), from NQIT's Co-Director for User Engagement, one of our researchers in Cambridge, and an expert in RRI from UCL. These talks were followed by a question and answer session, which gave people the opportunity to engage in more depth with our panel, and finally a networking session. Attendees appreciated "seeing wider opportunities from current near-home engagement" and "improvement of my knowledge of quantum technology". We will use other feedback to optimise future events.
Year(s) Of Engagement Activity 2016
URL http://www.nqit.ox.ac.uk/event/how-will-quantum-technologies-change-how-you-do-business
 
Description IET Lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Industry/Business
Results and Impact James Gates gave a talk titled 'Integrated optical circuits - from telecommunications to quantum computing' - highlighting the role that integrated photonic circuits play in a huge range of new industries
Year(s) Of Engagement Activity 2016
URL http://www.theiet.org/events/2016/228333.cfm
 
Description Key stage 3 school visits 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact 175 pupils in key stage 3 attended 2 events visiting the research organisation and taking practical classes on telecommunications and applications to photonics and manufacturing research. Positive change of attitude noted from both youths and accompanying teachers.
Year(s) Of Engagement Activity 2016
 
Description Lecture on quantum science at Seoul Science High School 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact M.S. Kim delivered a lecture at Seoul Science High School
Year(s) Of Engagement Activity 2014
 
Description Light Express Road Show 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact James Gates gave a lecture during Science Week (March 2014). It was a 50 minute Christmas lecture show including a laser show and experimental demonstrations. It demonstrated how a laser works, optical fibre and quantum photonics. Three, 50 minute shows to a total of ~900 adults and children.
Year(s) Of Engagement Activity 2014
 
Description Oxford Quantum simulation workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact S. Barz and C. di Franco organised the first junior researchers workshop on quantum simulation, for the members of BLOQS consortium held in Oxford in October 2015. Young researchers from around the world in the field of quantum simulation were invited to speak and discuss their research interests - a number of round table discussions and brainstorming sessions were held and new research directions were identified especially in the area of quantum chemistry simulations.
Year(s) Of Engagement Activity 2015
URL http://www.bloqs.org/#!Quantum-simulation-workshop/c12gu/56042e6c0cf2a7bb74b67955
 
Description Oxfordshire Science Festival 2016 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact In June 2016, NQIT's bid for a stall about quantum computing at the Oxfordshire science festival was successful, and we also received some funding to create new materials specifically aimed at engaging with the public. We designed banners, postcards and some games addressing the questions "Will a quantum computer change your life?", "What are we doing to make quantum computers a reality?", and "How do you build a quantum computer?". We used these materials at the festival to raise the visibility of quantum computing amongst the hundreds of members of the public who attended the free event. We also brought along some demonstrators of quantum technology, which a team of young researchers used to make quantum technologies accessible to the public.
Year(s) Of Engagement Activity 2016
URL http://www.oxfordshiresciencefestival.com/2016-festival-programme.html
 
Description Pint of Science talk - Peter Smith 2015 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Peter Smith gave a talk to around 50 members of the public in Southampton on "Nonlinear light: from missile defence to quantum computers" which introduced interested members of the public to the subject in an accessible way, and prompted discussion and interest in the research activity.
Year(s) Of Engagement Activity 2015
URL https://pintofscience.co.uk/event/light-the-future-of-the-internet/
 
Description Primary school workshops 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Work with university of southampton Outreach Office Widening Participation program. 3 events carried out to engage with 300 pupils from local schools.

The activity has resulted in the participation of a high-profile Primary Science Festival in Winchester Cathedral.
Year(s) Of Engagement Activity 2017
 
Description Quantum Technology for a Networked World: Clocks, GPS and all That 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact P. L. Knight delivered an evening public lecture at IBM Portsmouth on Quantum Technology for a Networked World organised by the IET and the IOP; attendance was about 250 people from industry, government and academia
Year(s) Of Engagement Activity 2014
 
Description Salisbury 6th Form Cleanroom Tours 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact James Gates and Matthew Posner organised a cleanroom tour to a group of Women Sixth Form students. The visit by the all-girls school was part of an initiative to encourage more young women to pursue studies in science and engineering.
Year(s) Of Engagement Activity 2015
URL http://www.orc.soton.ac.uk/q-wow.html
 
Description School visit (Inspire course) Key stage 5 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact 30 pupils from schools around the UK attended a workshop and visit of the research facilities of the Optoelectronics Research Centre as part of a residential course for girls. Change of attitude towards the subject area recorded and assimilation of knowledge and application of photonics research. Renewed interest to participate in the residential course in 2017.
Year(s) Of Engagement Activity 2016
 
Description Science and Engineering Day 2016 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact James Gates is organising a tour of the Mountbatten cleanrooms to show how quantum photonic devices are made.
Year(s) Of Engagement Activity 2016
 
Description TEAtime lectures 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact C Holmes presented
Year(s) Of Engagement Activity 2015
 
Description University of Southampton Science and Engineering Day 2015 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Peter Smith and James Gates organised tours of their NQIT lab, and 180 members of the public attended and expressed an interest in the research being conducted there. The wider festival at the University of Southampton attracted thousands of visitors.
Year(s) Of Engagement Activity 2015
URL https://www.southampton.ac.uk/assets/imported/transforms/content-block/UsefulDownloads_Download/0301...
 
Description Various School Outreach Events as part of the International Year of Light 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Matthew Posner organised and ran a series of outreach events in local schools as part of the University of Southampton's 'Lightwave' programme for the International Year of Light.

Key Stage 1 - 1 Events - 50 pupils
Key Stage 2 - 5 Events - 413 pupils
Key Stage 3 - 7 events - 507 pupils
Key Stage 4 - 1 event - 400 pupils
Sixth Form - 5 Events - 120 pupils
Year(s) Of Engagement Activity 2015
 
Description Winchester Cathedral Primary Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Participation in 2016 Winchester Cathedral Primary Science Festival. Working with 2 regional schools and 130 students in UK year 5-6.

The work has resulted in presentation of activity at an international conference, as well as a change of attitude and assimilation of knowledge from the youths participating in the activity.
Year(s) Of Engagement Activity 2016
URL https://blogs.unionsouthampton.org/blog/2016/11/25/opsoc-pgr-students-sheds-light-on-science-at-winc...