Multi-zone ion trap for Q20:20 node

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

Abstract

Project summary: This doctoral student project will contribute to the milestones of the Networked Quantum Information Technologies (NQIT) Hub, one of the UKNQTP's Quantum Technologies Hubs, which project falls within the EPSRC's Quantum Technologies research theme. In particular, the research the student will carry out in this project will impact on NQIT's milestones and deliverables in relation to the development of an engineered multiple ion trap, and reliable shuttling/splitting with mixed-species strings of ions. An essential requirement for the Q20:20 device, NQIT's flagship deliverable (to deliver a quantum computing demonstrator), is an ion trap node with several trapping zones (at least 3 zones), incorporating the ability to shuttle ions between zones with high reliability (<0.01% error). We will need to be able to split and recombine small strings of three or four ions, consisting of mixed species (Ca-43 and Sr-88 ions). The student will research methods for splitting and recombining these strings of ions.
For NQIT, we plan to use either the silicon traps developed by the National Physical Laboratory (NPL) Ltd (if the measured performance is sufficient) or gold-on-alumina wafer traps. A cryogenic (70K or 4K) vacuum system may be required to prevent ion loss or decrystallization, hence the design will need to be compatible with the cryogenic system to be developed in the ion trap group at the University of Sussex, which is a partner University in NQIT. This will mean that the student is required to collaborate closely with the researchers in Sussex, as well as those in Oxford, to ensure that the novel methodologies being developed in this project are compatible with the systems being built for NQIT in the two groups. An important task for the student will be to calculate the waveforms necessary for splitting, shuttling and recombining ion strings, and implement these using fast DACs to control electrode voltages.
The student will be able to take advantage of using the state-of-the-art facilities in Oxford, including shared resources such as laser sources, and a new clean room for assembly of microfabrication traps and UHV systems. These novel research methods developed in this student project will then be applied in the lab and refined by testing in the multi-zone trap.
There will be the potential to collaborate with NPL Ltd, with whom this research group is already in discussion about the use of their silicon trap, as referred to above, and also with Professor Winni Hensinger's ion trap group in Sussex, which uses a different design from the Lucas group's ion trap, but is working towards the same NQIT flagship deliverables. In addition to this, the student will benefit from Oxford graduate classes in quantum information processing, as well as working closely with experienced post-doctoral researchers working on developing the ion trap systems, who will give both supervision and support in the student's laboratory work. There will also be lots of opportunities to collaborate and interact with other researchers on the NQIT project.

Publications

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Sepiol MA (2019) Probing Qubit Memory Errors at the Part-per-Million Level. in Physical review letters

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509711/1 01/10/2016 30/09/2021
1793148 Studentship EP/N509711/1 01/10/2016 31/03/2020 Amy Hughes
 
Description We have characterised the performance of a "quantum memory", where information is stored in the internal energy states of a calcium ion. We measured the lowest memory errors reported to date in any physical system, at just a few ppm. A memory error this low offers greater flexibility in the design of a quantum computing system and algorithms, and puts us across the threshold for quantum error correction - an essential element for scaling up quantum computers.

We have demonstrated the world's highest fidelity (lowest error rate) entangling gate between two different species of ion, calcium and strontium. The fidelity achieved is comparable to the best entangling gates for a single ion species, despite the added experimental complexity that a second species brings. The ability to transfer information between different ion species allows us to combine advantages of elements which are well-suited for different tasks: for example, calcium makes for an excellent quantum memory, and strontium has properties which are desirable for networking tasks.

These are two important milestones related to the NQIT hub.
Exploitation Route Carefully characterised, high fidelity quantum memories and mixed-species logic gates open the door to scaling up quantum computing to more powerful systems. Applications include optimisations or risk minimisation calculations in sectors such as finance, defence and transport, or simulations of complex protein folding or chemical processes for the medical or chemical sectors. Our current experimental system offers the ability to demonstrate hybrid quantum-classical algorithms which have strict requirements on error rates.
Sectors Aerospace, Defence and Marine,Chemicals,Digital/Communication/Information Technologies (including Software),Electronics,Financial Services, and Management Consultancy,Healthcare,Transport