Coupling a ^{73}Ge Nuclear Spin to an Electrostatically Defined Quantum Dot in Silicon

Area of Science:

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

Background:

• Single nuclear spins in silicon offer long coherence times and high control fidelities for quantum technologies.
• Previous work encoded qubits and qudits on phosphorus-31 and antimony-123 nuclei.
• Isoelectronic nuclear spins, like silicon-29, coupled to quantum dots avoid charge issues and preserve nuclear spin coherence during electron shuttling.

Purpose of the Study:

• To demonstrate the coupling of a spin-9/2 germanium-73 nuclear spin to a gate-defined quantum dot in a silicon-on-insulator (SiMOS) platform.
• To investigate the hyperfine interaction (HFI) between the nuclear spin and the coupled electron.
• To establish a foundation for future quantum control experiments using nuclear spins as qudits.

Main Methods:

• Utilized Pauli spin blockade readout via radiofrequency (rf) reflectometry to detect the nuclear spin state.
• Employed gate voltage tuning to modify the hyperfine interaction strength.
• Integrated a spin-9/2 germanium-73 nuclear spin with a gate-defined quantum dot in a SiMOS structure.

Main Results:

• Successfully demonstrated the coupling between the germanium-73 nuclear spin and the quantum dot electron.
• Observed and tuned the hyperfine interaction (HFI) from 180 to 350 kHz by adjusting gate voltages.
• Achieved faster readout and smaller HFI, facilitating quantum non-demolition readout of the nuclear spin state.

Conclusions:

• The demonstrated coupling and tunable HFI pave the way for using spin-9/2 germanium-73 as a qudit in quantum information processing.
• This work enables future experiments on spin control, entanglement distribution between distant nuclear spins, and repeated weak measurements.