Spin Relaxation Benchmarks and Individual Qubit Addressability for Holes in Quantum Dots

Area of Science:

• Quantum Computing
• Solid-State Physics
• Materials Science

Background:

• Quantum dots are essential for quantum information processing.
• Hole spins in quantum dots are a promising qubit modality.
• Germanium offers unique properties for quantum dot development.

Purpose of the Study:

• Investigate hole spin relaxation in germanium quantum dots.
• Assess qubit addressability and electric field sensitivity.
• Determine the potential of germanium hole qubits for large-scale quantum computing.

Main Methods:

• Fabrication and characterization of a 2x2 germanium quantum dot array.
• Measurement of spin relaxation times (T1) for single and multihole occupations.
• Analysis of qubit resonance frequency dependence on gate voltages.

Main Results:

• Achieved spin relaxation times of 32 ms (single-hole) and 1.2 ms (five-hole).
• Demonstrated excellent individual qubit tunability with large resonance frequency tuning ranges.
• Observed weak dependence of resonance frequencies on neighboring gates, with a 20x higher sensitivity for five-hole qubits to their plunger gate.

Conclusions:

• Germanium hole quantum dots exhibit benchmark spin relaxation times.
• High qubit tunability and long coherence times position germanium holes as ideal for scalable quantum information.
• These findings pave the way for dense, high-fidelity quantum dot arrays.