Enhanced proximity effect in zigzag-shaped Majorana Josephson junctions

Understand

High density superconductor-semiconductor-superconductor junctions have a small induced superconducting gap due to the quasiparticle trajectories with a large momentum parallel to the junction having a very long flight time.

• Because a large induced gap protects Majorana modes, these long trajectories constrain Majorana devices to a low electron density.
• We show that a zigzag-shaped geometry eliminates these trajectories, allowing the robust creation of Majorana states with both the induced gap $E_\textrm{gap}$ and the Majorana size $\xi_\textrm{M}$ improved by more than an order of magnitude for realistic parameters.
• In addition to the improved robustness of Majoranas, this new zigzag geometry is insensitive to the geometric details and the device tuning.