A single-hole spin qubit

TL;DR

This paper demonstrates a single-hole spin qubit in germanium, achieving single-shot readout, quantum control, and long relaxation times, advancing the development of hole-based quantum computing hardware.

Contribution

It establishes the first single-hole spin qubit in germanium with integrated readout and control, surpassing previous multi-hole demonstrations.

Findings

Single-shot spin readout achieved in germanium quantum dot

Rabi driving demonstrates coherent control of the hole spin

Spin relaxation time exceeds one millisecond

Abstract

Qubits based on quantum dots have excellent prospects for scalable quantum technology due to their inherent compatibility with standard semiconductor manufacturing. While early on it was recognized that holes may offer a multitude of favourable properties for fast and scalable quantum control, research thus far has remained almost exclusively restricted to the simpler electron system. However, recent developments with holes have led to separate demonstrations of single-shot readout and fast quantum logic, albeit only in the multi-hole regime. Here, we establish a single-hole spin qubit in germanium and demonstrate the integration of single-shot readout and quantum control. Moreover, we make use of Pauli spin blockade, allowing to arbitrarily set the qubit resonance frequency, while providing large readout windows. We deplete a planar germanium double quantum dot to the last hole, confirmed by radio-frequency reflectrometry charge sensing, and achieve single-shot spin readout. To demonstrate the integration of the readout and qubit operation, we show Rabi driving on both qubits and find remarkable electric control over their resonance frequencies. Finally, we analyse the spin relaxation time, which we find to exceed one millisecond, setting the benchmark for hole-based spin qubits. The ability to coherently manipulate a single hole spin underpins the quality of strained germanium and defines an excellent starting point for the construction of novel quantum hardware.