Topological π Junctions from Crossed Andreev Reflection in the Quantum Hall Regime

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Topological Superconductivity

Background:

• Quantum Hall regime in a two-dimensional electron gas (2DEG) with Zeeman field at filling factor ν=1.
• Spin-orbit coupling is crucial for the observed phenomena.

Purpose of the Study:

• Investigate the creation of topological superconducting gaps.
• Explore the properties and tunability of these gaps.
• Demonstrate the potential for protected quantum operations.

Main Methods:

• Contacting a 2DEG with an s-wave superconductor strip.
• Analyzing crossed Andreev reflection (CAR) processes.
• Theoretical modeling of topological gap formation and Majorana zero modes.

Main Results:

• A topological superconducting gap is induced along the superconductor-2DEG contact.
• The gap's sign is controlled by CAR amplitude, tunable via Fermi wavelength and strip width.
• A π junction with opposite topological gaps hosts robust Majorana zero modes.

Conclusions:

• The proposed system allows for externally controlled topological superconductivity.
• Robust Majorana zero modes are realized in a configuration suitable for quantum computation.
• Protected non-Abelian tunnel-braid operations are achievable without fine-tuning.