Hole spin relaxation in Ge-Si core-shell nanowire qubits

Area of Science:

• Quantum Information Science
• Condensed Matter Physics
• Materials Science

Background:

• Controlling decoherence is crucial for quantum information hardware development.
• Electron spins in gallium arsenide face decoherence due to nuclear spin coupling.
• Group IV semiconductors offer low nuclear spin densities, ideal for spin qubits, but face fabrication challenges.

Purpose of the Study:

• To demonstrate state preparation, pulsed gate control, and charge-sensing spin readout of hole spins in a germanium-silicon core-shell nanowire.
• To investigate spin relaxation times and mechanisms in this novel quantum bit platform.

Main Methods:

• Fabrication of germanium-silicon core-shell nanowires.
• Implementation of fast gating techniques for qubit control.
• Charge-sensing spin readout for measuring qubit states.
• Measurement of spin relaxation times (T1) at varying magnetic fields.

Main Results:

• Successful demonstration of state preparation, pulsed gate control, and spin readout of hole spins.
• Measured spin relaxation times (T1) up to 0.6 ms in coupled quantum dots at zero magnetic field.
• Observed increase in relaxation time with decreasing magnetic field, consistent with a spin-orbit mechanism.

Conclusions:

• Hole spins in germanium-silicon nanowires present a viable platform for quantum information processing.
• The observed spin-orbit mechanism offers a pathway to mitigate decoherence in these devices.
• This work addresses key challenges in materials and interface control for solid-state quantum computing.