A singlet-triplet hole-spin qubit in planar silicon*

Spin Qubits in group IV materials are promising candidates for implementing quantum processors compatible with modern CMOS technology. Recently, hole spins have been demonstrated to be highly suitable for spin qubits, since the strong spin-orbit interaction for holes enables rapid all-electric spin control and offers a wide range of control over key parameters such as the g-tensor and spin coherence time [1]. However, to date there have been very few experimental demonstrations of hole-spin qubits, hence fundamental questions about the operation and optimisation of hole-spin qubits remain open.

In this work, we demonstrate a hole-spin qubit using a planar CMOS silicon technology [2]. The qubit is encoded into the singlet-triplet states of a double quantum dot, and the readout of the hole qubit is achieved using ambipolar charge sensing [3]. We observe Rabi oscillations (driven by g-factor differences) at frequencies exceeding 200MHz, making this amongst of the fastest spin-qubit platforms. We report measurements of the qubit T1 and T2* times and investigate the effect of magnetic field orientation on these key timescales, providing insights into the underlying spin-orbit physics. These results demonstrate that hole-spin qubits in planar silicon are competitive with state-of-the-art qubit platforms.

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[2] Liles, S. D., et al. Nat. communications 9.1 (2018); Liles, S. D., et al. Physical Review B 104.23 (2021): 235303.

[3] de Almeida, AJ Sousa, et al. Physical Review B 101.20 (2020): 201301.