Towards a depletion mode single-hole spin qubit in Ge

Group IV spin qubits are promising candidates for the realization of quantum processors due to their scalability, CMOS compatibility and long coherence times. In particular, Ge has become a very attractive platform because of the low effective mass and strong spin orbit interaction, which allows electrically driven spin qubits. From 2018 and within just three years a Loss-DiVincenzo (LD) [1], a singlet-triplet hole spin qubit [2], two-qubit gate devices [3] and a four-qubit Ge quantum processor [4] have been realized demonstrating the potential of Ge for quantum information [5]. Here we show our progress towards a depletion mode single-hole spin qubit in a Ge/SiGe heterostructure platform.

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[2] D. Jirovec, A. Hofmann, A. Ballabio, P. M. Mutter, G. Tavani, M. Botifoll, A. Crippa, J. Kukucka, O. Sagi, F. Martins, J. Saez-Mollejo, I. Prieto, M. Borovkov, J. Arbiol, D. Chrastina, G. Isella, G. Katsaros, A singlet-triplet hole spin qubit in planar Ge, Nature Materials (2021).

[3] N. W. Hendrickx, D. P. Franke, A. Sammak, G. Scappucci, M. Veldhorst, Nature 577, 487-491 (2020).

[4] N. W. Hendrickx, W. I. L. Lawrie, M. Russ, F. van Riggelen, S. L. de Snoo, R. N. Schouten, A. Sammak, G. Scappucci, M. Veldhorst, A four-qubit germanium quantum processor, Nature 591, 580-585 (2021).

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