Fluxoid-induced pairing suppression and near-zero modes in quantum dots coupled to full-shell nanowires

Abstract

We analyze the subgap excitations and phase diagram of a quantum dot (QD) coupled to a semiconducting nanowire fully wrapped by a superconducting (S) shell. We take into account how a Little-Parks (LP) pairing fluxoid (a winding in the S phase around the shell) influences the proximity effect on the dot. We find that under axially symmetric QD-S coupling, shell fluxoids cause the induced pairing to vanish, producing instead a level renormalization that pushes subgap levels closer to zero energy and flattens fermionic parity crossings as the coupling strength increases. This fluxoid-induced stabilization mechanism has analoges in symmetric S-QD-S Josephson junctions at phase $\pi$, and can naturally lead to patterns of near-zero modes weakly dispersing with parameters in all but the zero-th lobe of the LP spectrum.

17 pages, 8 figures. v2: final version with a new figure

References in corpus (8)

• Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• Shiba states and zero-bias anomalies in the hybrid normal-superconductor Anderson model
• Topological superconductivity in semiconductor-superconductor-magnetic insulator heterostructures
• Electronic structure of full-shell InAs/Al hybrid semiconductor-superconductor nanowires: Spin-orbit coupling and topological phase space
• Asymmetric Little-Parks Oscillations in Full Shell Double Nanowires
• Effects of the electrostatic environment on superlattice Majorana nanowires
• Topological superconductivity in tripartite superconductor-ferromagnet-semiconductor nanowires

Cited by in corpus (12)

• Singlet-doublet transitions of a quantum dot Josephson junction detected in a transmon circuit
• Theory of Caroli-de Gennes-Matricon analogs in full-shell hybrid nanowires
• Phenomenology of Majorana zero modes in full-shell hybrid nanowires
• Josephson effect and critical currents in trivial and topological full-shell hybrid nanowires
• Absence of Majorana oscillations in finite-length full-shell hybrid nanowires
• Subgap transport in superconductor--semiconductor hybrid islands: Weak and strong coupling regimes
• InP/GaSb core-shell nanowires: a novel hole-based platform with strong spin-orbit coupling for full-shell hybrid devices
• Enhancement of the Kondo effect in a quantum dot formed in a full-shell nanowire
• Caroli-de Gennes-Matricon Analogs in Full-Shell Hybrid Nanowires
• Fluxoid valve effect in full-shell nanowire Josephson junctions
• Fluxoid solitons in superconducting tapered tubes and bottlenecks
• Absence of Quasi-Majorana False Positives in Full-Shell Hybrid Nanowires