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arXiv · 2412.09574

Omnidirectional shuttling to avoid valley excitations in Si/SiGe quantum wells

Róbert Németh·Vatsal K. Bandaru·Pedro Alves·Emma Brann·Owen M. Eskandari·Hudaiba Soomro·Avani Vivrekar·M. A. Eriksson·Merritt P. Losert·Mark Friesen
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Abstract

Conveyor-mode shuttling is a key approach for implementing intermediate-range coupling between electron-spin qubits in quantum dots. Initial implementations are encouraging; however, long shuttling trajectories are guaranteed to encounter regions of low conduction-band valley energy splittings, due to the presence of random-alloy disorder in Si/SiGe quantum wells. Here, we theoretically explore two schemes for avoiding valley-state excitations at these valley-splitting minima, by allowing the electrons to detour around them. A multichannel shuttling scheme allows electrons to tunnel between parallel channels, while a two-dimensional (2D) shuttler provides full omnidirectional control. Using simulations, we estimate shuttling fidelities in these two schemes, obtaining a clear preference for the 2D shuttler. Based on such encouraging results, we propose a modular qubit architecture based on 2D shuttling, which enables all-to-all connectivity within qubit plaquettes and high-fidelity communication between different plaquettes.

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Róbert Németh, Vatsal K. Bandaru, Pedro Alves, Emma Brann, Owen M. Eskandari, Hudaiba Soomro, Avani Vivrekar, M. A. Eriksson, Merritt P. Losert, Mark Friesen. 2024-12-12. Omnidirectional shuttling to avoid valley excitations in Si/SiGe quantum wells. https://doi.org/10.1103/615j-xjyh

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