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Making quantum processors with spin qubits

Stephan Philips (TU-Delft)


Horaire/Time : le mardi 14 juin 2022 à 14:00


Lieu/Place : Visio-conférence Zoom hybride depuis Salle Rémy Lemaire K223, Institut Néel

Zoom link : https://univ-grenoble-alpes-fr.zoom.us/j/91808901596?pwd=UWZ2cml2N1VBOEZBenk0d3RJek9rdz09


Resumé/Abstract: A Future quantum computers capable of solving relevant problems will require a large number of qubits that can be operated reliably(1). However, the requirements of having a large qubit count and operating with high-fidelity are typically conflicting. Spins in semiconductor quantum dots show long-term promise but demonstrations so far use between one and four qubits and typically optimize the fidelity of either single- or two-qubit operations, or initialization and readout (2,3,4,5,6,7,8). Here (9) we expand the number of qubits and simultaneously achieve respectable fidelities for universal operation, state preparation and measurement. We design, fabricate and operate a six-qubit processor with a focus on careful Hamiltonian engineering, on a high level of abstraction to program the quantum circuits and on efficient background calibration, all of which are essential to achieve high fidelities on this extended system. State preparation combines initialization by measurement and real-time feedback with quantum-non-demolition measurements. These advances will allow testing of increasingly meaningful quantum protocols and constitute a major stepping stone towards large-scale quantum computers. In this talk I will briefly review electron spin qubits and explain the results described above.

1. Vandersypen, L. M. K., et al., npj Quantum Information, vol. 3.1, pp. 1-10, 2017.
2. Veldhorst, M., et al, Nature nanotechnology, vol. 9.12, pp. 981-985, 2014.
3. Yoneda J., et al., Nature Nano, vol. 13, pp. 102-106, 2018.
4. Xue X., et al, Nature 601, 343–347, 2022
5. Noiri, A.et al., Nature 601, 338–342, 2022
6. Mills, A.et al., arXiv:2111.11937, 2021
7. Takeda K., et al., Nature Nano, pp. 1-5, 2021.
8. Hendrickx N. W., et al., Nature, vol. 591, pp. 580–585, 2021
9. Philips S., Mądzik M, et al., https://arxiv.org/abs/2202.09252