Pauli spin blockade in a highly tunable silicon double quantum dot.

Area of Science:

• Quantum Computing
• Solid-State Physics
• Materials Science

Background:

• Double quantum dots are promising solid-state platforms for quantum information encoding.
• Pauli spin blockade, based on the Pauli exclusion principle, allows detection and manipulation of two-electron spin states.
• Isotopic purification in silicon can create environments free of nuclear spins, crucial for preserving coherent spin states.

Purpose of the Study:

• To engineer and investigate a gate-defined silicon metal-oxide-semiconductor double quantum dot system.
• To demonstrate and characterize Pauli spin blockade in this system.
• To assess the potential for realizing singlet-triplet qubits.

Main Methods:

• Fabrication of a gate-defined silicon metal-oxide-semiconductor double quantum dot.
• Independent electrostatic tuning of electron occupancy and inter-dot tunnel coupling.
• Measurement of Pauli spin blockade and singlet-triplet splitting.
• Analysis of leakage current's magnetic field dependence.

Main Results:

• Clear observation of Pauli spin blockade at weak inter-dot coupling.
• Measurement of a large intra-dot singlet-triplet splitting exceeding 1 meV.
• Observation of peculiar magnetic field dependence in leakage current, attributed to spin-flip cotunneling.

Conclusions:

• The engineered silicon double quantum dot system effectively demonstrates Pauli spin blockade.
• The observed phenomena, particularly spin-flip cotunneling effects, provide insights into spin dynamics.
• The system shows excellent prospects for the realization of singlet-triplet qubits.