Demonstration of Microwave Resonators and Double Quantum Dots on Optimized Reverse-Graded Ge/SiGe Heterostructures.

Area of Science:

• Quantum computing
• Condensed matter physics
• Materials science

Background:

• Planar germanium quantum wells (Ge QWs) in silicon-germanium (SiGe) barriers are promising for spin-based quantum computing.
• Reverse linear grading offers thin, low-roughness heterostructures but lacks demonstrated compatibility with superconducting resonators.

Purpose of the Study:

• To investigate the compatibility of reverse-graded Ge/SiGe heterostructures with superconducting microwave resonators.
• To realize well-controlled quantum dots and high-quality resonators on the same chip.

Main Methods:

• Growth of Ge/SiGe heterostructures using the reverse linear grading approach.
• Fabrication of coplanar waveguide resonators.
• Characterization of double quantum dots within the heterostructure.

Main Results:

• Successful fabrication of high-quality coplanar waveguide resonators on reverse-graded Ge/SiGe heterostructures.
• Demonstration of well-controlled double quantum dots in the same material system.
• Compatibility between quantum confinement and superconducting resonator fabrication is established.

Conclusions:

• Reverse-graded Ge/SiGe heterostructures are suitable for integrated quantum computing architectures.
• This work paves the way for scalable quantum information processing using germanium quantum dots.