Advancing quantum machine learning experiments using high-efficiency molecular photon sources

Advancing quantum machine learning experiments using high-efficiency molecular photon sources

Are you interested in doing a PhD in the burgeoning field of quantum technologies? This project, ‘Advancing quantum machine learning experiments using high-efficiency molecular photon sources’ is part of five fully-funded studentships available across a number of potential research areas within University of Bristol’s Quantum Engineering Technology Labs (QET Labs), to commence September/October 2024. To view the additional PhD projects available and apply, please visit the QET Labs website via this link.

Project description

Quantum interference using multiple photons is a key technique for advancing a wide range of quantum technologies [1], ranging from quantum information processing and simulation to communications and networking. The escalating demands of these technologies necessitate the simultaneous generation and detection of an increasing number of photons, requiring photon sources to operate at high efficiencies. However, traditional methods such as spontaneous photon pair generation are constrained by inherently low efficiencies to avoid the production of multiple photon pairs. On the other hand, single quantum emitters, although capable of emitting one photon at a time, are hampered by poor collection efficiencies. This project addresses the latter problem by integrating tunable micro-cavities at the end of an integrated photonic waveguide array and coupling single organic molecules into these cavities [2]. Your role will be to design silicon nitride waveguides and mode-matched distributed Bragg reflectors, which will be combined with bending piezoelectric transducers to form tunable open-access cavities. You will then embed organic crystals containing fluorescent molecules into these cavities to enable high-efficiency photon generation directly into the integrated silicon nitride waveguides. Your research will subsequently extend to the design of photonic waveguide interferometers and devices compatible with the fabricated cavities to enable multi-photon interference. This will facilitate the training of variational quantum circuits (VQCs) for quantum machine learning applications [3]. VQCs, the quantum counterparts to classical neural networks, consist of parametrized quantum circuits where parameter optimisation is undertaken by classical optimisers [4]. These circuits are widely considered to be among the most promising candidates for demonstrating quantum advantage in practical applications. They hold potential not only for tasks that are inherently quantum, such as studies in chemistry and materials science, but also for classical optimisation problems and supervised machine learning [5]. The enhanced photon production capabilities developed in this project will significantly reduce the data acquisition times typically required for VQC training, particularly in multi-photon experiments. This highly collaborative project will thus entail a thorough exploration of foundational photonics technologies, while also addressing open problems at the frontier of quantum machine learning.

To apply for this project, or any of the other projects available within QET Labs, please use our online application form, and select “Physics (PhD)” as the programme. You will need (1) a CV, (2) a Personal Statement, which is a one- to two-page document introducing yourself and outlining your motivation for PhD research, and (3) a transcript of any qualifying degrees (completed and/or underway). Whilst a research proposal is not required by the School of Physics, it is a required document on the application portal and therefore a blank document can be uploaded instead. We strongly encourage applications from home candidates and candidates from underrepresented groups. At the top of your personal statement, please state clearly that you are applying for a PhD within the Quantum Engineering Technology Labs, and state which of the PhD projects you are interested in. QET Labs supports Diversity and Equality, and we invite all eligible candidates to apply. We encourage applications from under-represented groups. Within the School of Physics, we hold a Silver Athena Swan award and a Physics Juno Champion award.

Early application is encouraged. The closing date for applications to this call is midnight Monday 3rd June.

QETLabs: A world-class research environment

The Quantum Engineering Technology Labs has the broad remit of accelerating application of quantum technologies, developing new capabilities and hardware that use quantum phenomena, and to explore fundamental quantum information science with new technology. QET Labs benefits from state-of-the-art facilities, including fully equipped quantum optics laboratories in the School of Electrical, Electronic and Mechanical Engineering and the School of Physics, integrated quantum photonics characterisation suites, ultra-low vibration noise facilities in the Nanoscience and Quantum Information building and device nano-fabrication in the University cleanroom.

Physics at Bristol was ranked 5th for Research in the 2022 Research Excellence Framework (REF) results, and the University of Bristol is truly world-leading: 55th in the QS World University Ranking (2024) and 81st in the Times Higher Ranking (2024).

What does a Scholarship cover?

For successful students, the scholarships will cover living expenses (UKRI rate), University tuition fees (see PhD Physics Study at Bristol University of Bristol) and consumables.

The Bristol Graduate Research Community

If successful, you will become a member of either the Physics or Engineering Graduate School, vibrant and diverse communities of 200-plus research students from a wide range of countries and backgrounds. The Graduate Schools run comprehensive induction programmes to get you off to the best possible start in your research, and rolling programmes of targeted skills training in writing, presenting, project-planning, etc. The Schools operate a “one-stop shop” approach to help you navigate through the University procedures, organise meetings for postgraduate opportunities and support in transitioning to post-PhD careers, connecting you to the wider University, including the Bristol Doctoral College, www.bristol.ac.uk/doctoral-college/.

What are the candidate requirements?

A first degree in physics, engineering, chemistry, computer science, or a related subject, normally at a level equivalent to at least UK upper second-class honours, or a relevant postgraduate master’s qualification. Please see Applying from your country International students University of Bristol on the International Office website.

English language requirements

If English is not your first language, you need to meet English Language Profile F. Further information about this can be found here: English language requirements Study at Bristol University of Bristol

Admissions Statement: https://bristol.ac.uk/study/media/postgraduate/admissions-statements/2023/phd-physics.pdf

Contacts and further information

Please contact the QET Labs enquiries mailbox (qetlabs-enquiries@bristol.ac.uk).