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Conveyor-mode single-electron shuttling in Si/SiGe

Kolloquium der Abteilung 2

One- and two-qubit manipulation fidelity of spin qubits in silicon has been increased to the point at which quantum error correction is possible, if the qubit platform becomes scalable.

One missing key technology for this scale-up is a coherent medium-range coupling between two qubits at 1 to 10 µm distance. It would enable a sparse-qubit architecture and makes space for signal-line fan-out and cryogenic electronics tiles integrated on the qubit chip [1].

I present an approach named conveyor-mode shuttling, which relies on physically transporting the electron representing the qubit by a propagating wave-potential across an electrostatically defined Si/SiGe quantum-channel [2]. We demonstrated shuttling of a single electron across a distance of 420 nm using only four sinusoidal control signals [3] and observed a high single-electron shuttling fidelity of >99 % including a reversal of transport direction. I will show first experiments on spin-coherent shuttling and discuss the perspective to reach a qubit transfer fidelity of  99.9 % across a distance of 10 µm [2].

[1] J. M. Boter et al., Spiderweb Array: A Sparse Spin-Qubit Array. Phys. Rev. Appl. 18, 024053 (2022).

[2] V. Langrock et al., Blueprint of a scalable spin qubit shuttling device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO2, arxiv:2202.11793v2 (2022).

[3] I. Seidler et al., Conveyor-mode single-electron shuttling in Si/SiGe for a scalable quantum computing architecture. npj Quantum Inf. 8:100 (2022).