Microwave to optical quantum transducers using travelling wave phonons

About the Project

Microwave to optical quantum transducers using travelling wave phonons

Research Project

A logical next step for current noisy intermediate scale quantum (NISQ) computing platforms, following the historical development of classical information platforms is figuring out ways to interconnect small remote quantum processors together to take the first steps towards the envisioned quantum network. Such networking efforts need to proceed in parallel to the current efforts on developing error correction / logical qubits as it is relatively clear that both things need to be achieved for useful quantum computing to be deployed. While this networking problem is of general interest across all quantum platforms, it is of particular importance for superconducting qubit based systems as without networking, there are physical limits imposed by size and cooling constraints, that ultimately limit how far these qubits can scale. This is best exemplified by the recent Google call for academic research partnerships which was exclusively focused on transduction and these ideas are also now appearing on IBM’s quantum roadmap. In a broader sense, the UK’s quantum technology mission #1 (trillion operations) and #2 (networked quantum) implicitly require that this problem be addressed.

In this project, we focus on building such efficient microwave to optical signal transducers using acoustic waves as an intermediary. Acoustics solves the wavelength mismatch problem between the microwave and optical frequency domains by providing access to GHz frequencies at µm wavelengths enabling strong acousto-optic interactions to be engineered in nanoscale systems (see Balram and Srinivasan, doi:10.1002/qute.202100095 for a recent review). We aim to demonstrate efficient transducers in an unsuspended geometry which supports both guided acoustic and optical fields and strong acousto-optic interaction (analog of Brillouin scattering). While the AO interaction strength is weaker than in the traditional 1D opto-mechanical crystals, the phonon injection efficiency is considerably higher and provided low acoustic and optical loss are achieved, the overall efficiency, manufacturability and scalability of this platform is promising.

This project is available to UK home candidates only, and is an industry co-sponsored studentship within the Quantum Information Science and Technologies (QIST) CDT, an EPSRC funded Centre for Doctoral Training jointly hosted at University of Bristol and University of Sussex.

A world-class environment for your research degree

The School of Physics is offering a portfolio of PhD Scholarships across all its world-class research groups. These prestigious Scholarships represent a great opportunity to start your Postgraduate Research Career working with world-class academics in a supportive training and development environment. 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 home students, the scholarships will cover living expenses (UKRI rate), University tuition fees (see PhD Physics | Study at Bristol | University of Bristol), and training and support expenses.

The Bristol Physics Graduate Research Community

If successful, you will become a member of the Physics Graduate School, a vibrant and diverse community of 200-plus research students from a wide range of countries and backgrounds. The Graduate School:

• runs a comprehensive induction programme to get you off to the best possible start in your research, and a rolling programme of targeted skills training on writing, presenting, project-planning, etc.
• operates a “one-stop shop” approach to help you navigate through the University procedures
• organises meetings for postgraduate opportunities, and support in transitioning to post-PhD careers
• connects you to the wider University, including the Bristol Doctoral College, www.bristol.ac.uk/doctoral-college/.

How do I apply?

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).

You do not need a research proposal, but are encouraged to specify a research theme or academic supervisor. Please contact the academics within the School of Physics research areas for information.

Applicants will be assessed on merit, and interviews will be held for shortlisted applicants.

You need to apply through the University of Bristol application system at http://www.bristol.ac.uk/study/postgraduate/apply/. Please select Physics PhD on the Programme Choice page. The School of Physics supports Diversity and Equality, and we invite all eligible candidates to apply. We encourage applications from under-represented groups. We hold a Bronze Athena Swan award and a Physics Juno Champion award.

What are the candidate requirements?

A first degree in physics 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 Bristol Physics Graduate School at: physics-pg@bristol.ac.uk