Scalable implementation of hybrid spin qubits in CMOS-compatible devices

Lead Research Organisation: University College London
Department Name: London Centre for Nanotechnology


A quantum computer will solve problems that are impossible even for classical supercomputers to solve in reasonable time. Theoretical studies have indicated an expected "quantum speed-up" over classical computers in applications such as cryptography, optimization and simulation. However, to achieved this quantum speed-up requires large number of accessible qubits with extremely high fidelity. Current quantum technology offered few tens of qubits with barely satisfactory multi-qubit gate fidelity, and still it faces scaling up issues both in qubits as well as in peripheral control circuitry. Researchers have demonstrated qubits constructed from the spin states of impurity donors or quantum dots in silicon(Si) substrates with record-high coherence times. Meanwhile, Si-based qubits could potentially scale up benefiting from the standard industrial complementary metal oxide semiconductor (CMOS) processes. CMOS processes have been developing for the past few decades and state-of-art process can produce billions of transistors within a cm-scale chip. Therefore, silicon spin qubits are very promising candidates for quantum computing based on its robust storage of quantum information and possibility to leverage mature manufacturing processes. This project will investigate a possible spin qubit implementation based on silicon Nanowire Field Effect Transistors (Si NW-FETs). Quantum dots, or potentially donors located within the FET channel, will be used as the qubits, and strategies for using global control to improve scaling will be investigated. Qubit coupling using floating gates will be evaluated, and techniques to achieve high-fidelity spin read-out using reflectometry will be optimised.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/P510270/1 31/03/2016 30/08/2022
1937065 Studentship EP/P510270/1 24/09/2017 31/12/2021 JINGYU DUAN
Description One objective of this award is the hybrid-spin system which requires two elements normal quantum dot (artificial atom) and bismuth atom. Quantum dot has been studied in the various system in different groups while single bismuth atom has never been observed. In the investigation of the research, we have proofs that we observe both of ingredients which is an essential step towards implementing this qubit in this system.
Another objective is the scalability of the system for quantum computing. In the past year, I have studied the coupling mechanism in a rather long distance. This work is published in a peer-reviewed journal.
On a side project, I have studied a new type of device which compares the electron and holes in the same experiment. A paper has been submitted and is currently under review.
Exploitation Route if both of the objectives were achieved at the end of this award. Industrial can refer to the result to fabricate similar devices and make a scalable quantum computer which has a great benefit on solving complex problems that classical computers may not achieve in any feasible timescale.
Sectors Digital/Communication/Information Technologies (including Software),Electronics

Description CDT Sandpit event 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact 10 students to work through a series of group exercises to come up with some ideas for group projects, which they will then present to a panel of academics on the 21st. I help facilitate the discussions during the various group exercises
Year(s) Of Engagement Activity 2021