Fano effect in Aharonov-Bohm ring with topologically superconducting bridge

Area of Science:

• Condensed Matter Physics
• Quantum Transport Phenomena
• Topological Superconductivity

Background:

• Aharonov-Bohm (AB) rings are crucial for studying quantum interference effects.
• Superconducting (SC) wires with strong spin-orbit interaction (SOI) exhibit topological properties.
• Understanding transport through SC wires requires considering their inner structure and bound states.

Purpose of the Study:

• To analyze transport features in an AB ring with an inner-structured SC wire.
• To investigate topological phase transitions induced by strong spin-orbit interaction (SOI).
• To explore the role of Majorana and Andreev bound states (MBS/ABS) in transport resonances.

Main Methods:

• Utilized nonequilibrium Green's functions within the tight-binding approximation.
• Analyzed the in-plane magnetic-field dependence of linear-response conductance.
• Investigated the influence of Coulomb interactions and disorder in the SC wire.

Main Results:

• Identified Breit-Wigner and Fano resonances (FRs) in the nontrivial topological phase.
• Attributed FRs to interacting transport channels and bound states in continuum (BSCs).
• Demonstrated extreme sensitivity of FR width and position to MBS vs. ABS.

Conclusions:

• FRs in the AB ring system are directly linked to the nature of bound states (MBS or ABS) in the SC wire.
• Specific T-shaped AB ring geometry shows FR disappearance with MBS, leading to quantized conductance.
• The presence of MBS or ABS significantly alters local conductance, with implications for topological quantum computing.