MQCQE seminar by Dr Andre Saraiva (UNSW) : SMART Dressing for Spins in a Global Field

August 19, 2021 @ 1:00 pm - 2:00 pm

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Title: SMART Dressingfor Spins in a Global Field

Abstract:Spins are quintessential qubits — a natural two-level system with longcoherence times and a small footprint in solid-state devices. However, movingfrom few qubit demonstrations to full scale processors creates a demand forrethinking the way these qubits are designed. Firstly, we will expose thechallenges for spin-based qubit scalability, particularly in the context ofsilicon quantum dots. An architecture that remedies many of these challengeswill then be explained, where qubits are set not by the spin’s direction, butby its state of movement under a driving electromagnetic field, known asdressed spin qubits. We will discuss how to i) generate such global field forcoherent spin control [1]; ii) harmonise all the necessary operations in aquantum processor with the always-on field [2]; and iii) leverage a geometricalvisualisation of the dynamical decoupling to devise a more resilient protocolfor qubit dressing, called the SMART (sinusoidally modulated, always-rotatingand tailored) protocol [3]. We finalise by showing a single qubit experimentalprototype using the SMART protocol to improve qubit coherence by orders ofmagnitude and perform logical gates with sufficient fidelity for fault-tolerantquantum computation [4]. This change in the prism by which qubits are seenopens the possibility for scalable, robust, universal quantum computing.

[1]Vahapoglu, E., Slack-Smith, J. P., Leon, R. C. C., Lim, W. H.,Hudson, F. E., Day, T., … & Pla, J. J. (2021). Coherent control ofelectron spin qubits in silicon using a global field. arXiv preprintarXiv:2107.14622.

[2]Seedhouse, A. E., Hansen, I., Laucht, A., Yang, C. H., Dzurak,A. S., & Saraiva, A. (2021). Quantum computation protocol for dressed spinsin a global field. arXiv preprint arXiv:2108.00798.

[3]Hansen, I., Seedhouse, A. E., Saraiva, A., Laucht, A., Dzurak,A. S., & Yang, C. H. (2021). The SMART protocol–Pulse engineering of aglobal field for robust and universal quantum computation. arXiv preprintarXiv:2108.00776.

[4]Hansen, I., Seedhouse, A. E., Chan, K. W., Hudson, F., Itoh, K.M., Laucht, A., … & Dzurak, A. S. (2021). Implementation of the SMARTprotocol for global qubit control in silicon. arXiv preprint arXiv:2108.00836.


Andre Saraiva is a Solid-State Physicist, interested in theelectronic structure theory of semiconductor devices used for quantum computingwith spins, as well as general theoretical questions about quantum processorcontrol, scalability and noise processes. He received a B.Sc., a M.Sc. and aPh.D. in Physics from the Universidade Federal do Rio de Janeiro in 2006, 2008and 2011, respectively. He was an Adjunct Professor of Physics at theUniversidade Federal do Rio de Janeiro, in Brazil, before he started hiscurrent work as a Senior Lecturer in the School of Electrical Engineering andTelecommunications at the University of New South Wales, in Australia.

Thu, August 19, 1pm – 2pm

MQCQE seminar by Dr Andre Saraiva (UNSW)

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August 19, 2021
1:00 pm - 2:00 pm
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