Undoped accumulation-mode Si/SiGe quantum dots

Area of Science:

• Quantum Information Science
• Condensed Matter Physics
• Materials Science

Background:

• Quantum dots are essential building blocks for quantum computers.
• Controlling electron tunneling in quantum dots is critical for device functionality.
• Silicon-germanium (SiGe) heterostructures offer low disorder for high-quality quantum dots.

Purpose of the Study:

• To present a new quantum dot device design.
• To demonstrate precise control over quantum dot electron occupancy and tunneling.
• To enable scalable quantum information processing.

Main Methods:

• Utilized undoped SiGe heterostructures for low disorder.
• Implemented an overlapping gate stack for unique gate functions.
• Controlled individual quantum dot occupancies and lateral tunneling.
• Measured tunneling rates over nine orders of magnitude.

Main Results:

• Demonstrated independent control of gate functions.
• Achieved precise control over tunneling rates between dots and electron baths.
• Quantified inter-dot tunnel coupling using anti-crossing measurements.
• Found exponential dependence of tunneling on gate voltage.

Conclusions:

• The novel SiGe quantum dot design enables precise control over quantum phenomena.
• This device architecture is promising for scalable quantum computing.
• The demonstrated control is essential for building robust qubits.