PhD Studentship: Time-bin Ion-photon Entanglement for Scalable Quantum Computing

A fully funded, 3.5-year PhD position is available in the Ion Trap Cavity-QED and Molecular Physics (ITCM) Group in the Department of Physics & Astronomy at the University of Sussex. The project is within the Quantum Computing and Simulation Hub.

For more information, please contact Prof Matthias Keller ([email protected] ). 

Application Deadline: 24th May 2024

Introduction:

This project unites two areas of quantum information processing: single ions stored in radio-frequency traps and single photons in optical fibres. Both fields have seen spectacular advances in recent years with the ITCM group having a leading role. Strings of ions are presently the most successful implementation of quantum computing. Photons, however, are used to distribute entanglement over ever-increasing distances.

The principal challenge is to enhance quantum processing power by scaling up current devices to larger quantum systems. We’re pursuing a promising strategy, distributed quantum computation, where multiple small-scale ion processors are interlinked by exchanging photonic quantum bits via optical fibres. This requires novel ion trap structures that facilitate high-performance quantum computation and a photonic interconnect for networking. 

Project:

The project investigates different schemes to generate and measure ion-photon entanglement using time-bin encoding, a crucial building block for photonic interconnects in quantum computers. We’ll extend previous research to produce time-bin entanglement and detection with high efficiency. Our ion-cavity system will generate time-bin encoded ion-photon entanglement by driving a bi-chromatic cavity-assisted Raman transition from the ion’s initial state to its final qubit states, generating a single entangled photon in the cavity. By delaying one of the Raman transitions, time-bin encoded ion-photon entanglement can be generated. To optimise the entanglement rate and fidelity, the process will be simulated and subsequently experimentally verified. Instead of using the ion’s fluorescence for entanglement measurement, the ion’s state will be mapped onto a second photon (state detection photon). Delaying the entangled photon to arrive at the input of a beam splitter in coincidence with the state detection photon enables measurement of correlations between the outputs of the beam splitter. This, together with state manipulation of the ion between the photon emissions, enables the tomography of the entanglement at a faster rate than measuring the ion’s quantum state directly. The project outcome is a demonstration of time-bin encoding with unparalleled efficiency and fidelity, a first demonstration of this as a method for truly scalable trapped ion-based quantum computers. 

Skills and training:

Skills development and training will be provided through lectures, transferable skills modules and practical laboratory based training, as well as SEPnet-wide training workshops and events.

Award Amount:

£18,622 per annum tax-free bursary and waiver of UK fees each year for 3.5 years, plus research training and travel funding. Additional funding may also be available to support placements with outside partners for a further period of six months. 

Eligibility:

Applicants should hold or expect to hold, a UK or equivalent undergraduate degree in physics or engineering.  To check the equivalence of your qualifications, please contact us at [email protected]

Due to funding restrictions, the studentship is open to UK residents only.

Procedure:

Apply online via the University of Sussex portal, http://www.sussex.ac.uk/study/phd/apply . State in the Funding section of the application form that you are applying for "MPS/2023/EAP/01”.