A four-qubit germanium quantum processor

First demonstration of a four-qubit quantum processor in germanium (Ge/SiGe) hole spin qubits. Demonstrates universal quantum logic including single-qubit gates, two-qubit CNOT, and four-qubit GHZ state preparation. Germanium’s strong spin-orbit coupling enables all-electrical control without micromagnets.

Key Results

• 4 hole spin qubits in a 2×2 Ge/SiGe quantum dot array
• Single-qubit fidelity: 99.3% (randomized benchmarking)
• Two-qubit CZ gate via exchange interaction
• All-electrical control (no micromagnets or ESR — spin-orbit-driven EDSR)
• Operated at ~20 mK

Links

• Journal: Nature
• arXiv: 2009.04268

Zoo Links

• hole-spin-qubit
• silicon-spin-qubit
• spin-qubit