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Destructive interference of direct and crossed Andreev pairing in a system of two nanowires coupled via an s-wave superconductor

Reeg, Christopher and Klinovaja, Jelena and Loss, Daniel. (2017) Destructive interference of direct and crossed Andreev pairing in a system of two nanowires coupled via an s-wave superconductor. Physical Review B, 96 (8). 081301.

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Official URL: https://edoc.unibas.ch/60924/

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Abstract

We consider a system of two one-dimensional nanowires coupled via an s-wave superconducting strip, a geometry that is capable of supporting Kramers pairs of Majorana fermions. By performing an exact analytical diagonalization of a tunneling Hamiltonian describing the proximity effect (via a Bogoliubov transformation), we show that the excitation gap of the system varies periodically on the scale of the Fermi wavelength in the limit where the interwire separation is shorter than the superconducting coherence length. Comparing with the excitation gaps in similar geometries containing only direct pairing, where one wire is decoupled from the superconductor, or only crossed Andreev pairing, where each nanowire is considered as a spin-polarized edge of a quantum Hall state, we find that the gap is always reduced, by orders of magnitude in certain cases, when both types of pairing are present. Our analytical results are further supported by numerical calculations on a tight-binding lattice. Finally, we show that treating the proximity effect by integrating out the superconductor using the bulk Green`s function does not reproduce the results of our exact diagonalization.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretical Nano/Quantum Physics (Klinovaja)
UniBasel Contributors:Klinovaja, Jelena
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Physical Society
ISSN:2469-9950
e-ISSN:2469-9969
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:07 Mar 2018 14:26
Deposited On:07 Mar 2018 14:26

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