Spin Relaxation in Ge/Si Core-Shell Nanowire Qubits

TL;DR

This paper demonstrates the development of Ge/Si core-shell nanowire spin qubits, achieving significant control over hole spins, with relaxation times approaching 1 ms, advancing nuclear-spin-free quantum computing platforms.

Contribution

It presents the first steps in implementing spin qubits in Ge/Si nanowires, including state preparation, pulsed control, and spin readout, highlighting improved relaxation times.

Findings

Achieved spin relaxation times approaching 1 ms.

Demonstrated state preparation and pulsed control of hole spins.

Observed relaxation times increase at lower magnetic fields.

Abstract

Controlling decoherence is the most challenging task in realizing quantum information hardware. Single electron spins in gallium arsenide are a leading candidate among solid- state implementations, however strong coupling to nuclear spins in the substrate hinders this approach. To realize spin qubits in a nuclear-spin-free system, intensive studies based on group-IV semiconductor are being pursued. In this case, the challenge is primarily control of materials and interfaces, and device nanofabrication. We report important steps toward implementing spin qubits in a predominantly nuclear-spin-free system by demonstrating state preparation, pulsed gate control, and charge-sensing spin readout of confined hole spins in a one-dimensional Ge/Si nanowire. With fast gating, we measure T1 spin relaxation times in coupled quantum dots approaching 1 ms, increasing with lower magnetic field, consistent with a spin-orbit mechanism that is usually masked by hyperfine contributions.