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Engineering Ge Profiles in Si/SiGe Heterostructures for Increased Valley Splitting
Lucas E A Stehouwer1, Merrit P Losert2, Maia Rigot1
1QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Researchers enhanced valley splitting in silicon-germanium quantum wells by growing thinner wells with broad interfaces. This approach boosts electron-spin qubit performance by increasing the energy separation of conduction-band valleys.
Area of Science:
- Quantum computing
- Condensed matter physics
- Materials science
Background:
- Electron-spin qubits in Si/SiGe quantum wells are hindered by small and variable valley splitting.
- Deterministic enhancement typically relies on sharp quantum-well interfaces.
Purpose of the Study:
- To explore an alternative method for enhancing valley splitting on average.
- To investigate the relationship between quantum well properties and valley splitting.
Main Methods:
- Growing thinner Si/SiGe quantum wells with broad interfaces.
- Increasing electron wave function overlap with Ge atoms.
- Conducting Quantum Hall measurements on 2D electron gases.
Main Results:
- A linear correlation was found between valley splitting and disorder-induced energy-level broadening.
- Enhanced valley splitting was achieved while maintaining good electron mobility.
- Simulations predicted similar valley splitting enhancements in quantum dots.
Conclusions:
- Broad interfaces in thinner quantum wells can effectively increase valley splitting.
- This approach offers a promising route for realizing quantum-dot spin qubits.
- The findings suggest a new strategy for optimizing qubit performance in Si/SiGe heterostructures.
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