Quantized conductance doubling and hard gap in a two-dimensional semiconductor-superconductor heterostructure

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Computing

Background:

• Coupling 2D semiconductors with superconductors is key for mesoscopic superconductivity and topological states.
• Previous attempts faced challenges with interface disorder and gating instability.
• Spin-orbit interaction in 2D electron gas is crucial for topological matter.

Purpose of the Study:

• To demonstrate a gateable InGaAs/InAs 2D electron gas (2DEG) coupled to epitaxial aluminum.
• To achieve atomically pristine semiconductor-superconductor interfaces.
• To explore the potential for low-dissipation electronics and topological quantum systems.

Main Methods:

• Fabrication of a gateable InGaAs/InAs 2DEG system with patterned epitaxial aluminum.
• Formation of a quantum point contact (QPC) using surface gates.
• Measurement of superconducting gap and conductance in the quantum point contact.

Main Results:

• Achieved atomically pristine interfaces between the semiconductor and superconductor.
• Observed a hard superconducting gap in the tunneling regime of the QPC.
• Recorded a first conductance plateau at 4e²/h in the open regime of the QPC.

Conclusions:

• The demonstrated hard-gap semiconductor-superconductor system offers a new route for topological quantum systems.
• The system is amenable to top-down processing, suitable for scalable superconducting electronics.
• This approach opens avenues for developing low-dissipation electronic devices.