Fast two-qubit logic with holes in germanium.

Area of Science:

• Quantum Information Science
• Solid-State Physics
• Materials Science

Background:

• Universal quantum information processing relies on single- and two-qubit logic gates.
• Spin qubits in quantum dots are promising for quantum computation, with control demonstrated in GaAs and silicon.
• Universal quantum logic with local control has not yet been achieved in these systems.

Purpose of the Study:

• To demonstrate universal quantum logic using hole quantum dots in germanium.
• To leverage germanium's properties for high-fidelity and fast qubit operations.
• To establish germanium as a viable platform for quantum information applications.

Main Methods:

• Utilized quantum wells with low disorder for precise control of tunnel coupling and detuning.
• Operated qubits at the charge symmetry point for enhanced performance.
• Exploited spin-orbit coupling for rapid qubit control at frequencies exceeding 100 MHz.

Main Results:

• Achieved single-qubit gates with 99.3% fidelity and 20 ns gate times.
• Demonstrated two-qubit logic operations within 75 ns.
• Established rapid qubit control enabled by spin-orbit coupling.

Conclusions:

• Germanium hole quantum dots enable fast, high-fidelity universal quantum logic.
• The demonstrated control and speed position germanium as a leading material for quantum information processing.
• This work significantly advances the development of scalable quantum computers.