Challenges in detecting topological superconducting transitions via supercurrent and phase probes in planar Josephson junctions

Fuente: arXiv
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Main Authors: Sharma, Pankaj, Mohanta, Narayan
Format: Preprint
Published: 2023
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author Sharma, Pankaj
Mohanta, Narayan
author_facet Sharma, Pankaj
Mohanta, Narayan
contents Topological superconductors harbor, at their boundaries and vortex cores, zero-energy Majorana bound states, which can be the building blocks in fault-tolerant topological quantum computing. Planar Josephson junctions host such topological superconducting phases, highly tunable by external magnetic field or phase difference between the superconducting leads. Despite many theoretical and experimental studies, the signatures of the transition to a topological superconducting phase, based on minima in the critical supercurrent $I_c$ flowing across the junction, $0$-$π$ transition in the ground state junction phase and their anisotropic magnetic-field response have remained unsettled. Using rigorous numerical calculations with several experimentally-relevant parameter settings, we show that $I_c$ and $φ_{_{\rm GS}}$ cannot indicate unambiguously topological transition in any realistic planar junctions. Furthermore, the anisotropic variations of $I_c$ and $φ_{_{\rm GS}}$ with in-plane magnetic field appear in junctions that are undoubtedly in trivial superconducting phase, raising concerns on the effectiveness of these probes in identifying topological transitions in planar junctions. We discuss possible strategies to confirm a topological superconducting phase in these platforms.
format Preprint
id arxiv_https___arxiv_org_abs_2307_11645
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Challenges in detecting topological superconducting transitions via supercurrent and phase probes in planar Josephson junctions
Sharma, Pankaj
Mohanta, Narayan
Superconductivity
Mesoscale and Nanoscale Physics
Topological superconductors harbor, at their boundaries and vortex cores, zero-energy Majorana bound states, which can be the building blocks in fault-tolerant topological quantum computing. Planar Josephson junctions host such topological superconducting phases, highly tunable by external magnetic field or phase difference between the superconducting leads. Despite many theoretical and experimental studies, the signatures of the transition to a topological superconducting phase, based on minima in the critical supercurrent $I_c$ flowing across the junction, $0$-$π$ transition in the ground state junction phase and their anisotropic magnetic-field response have remained unsettled. Using rigorous numerical calculations with several experimentally-relevant parameter settings, we show that $I_c$ and $φ_{_{\rm GS}}$ cannot indicate unambiguously topological transition in any realistic planar junctions. Furthermore, the anisotropic variations of $I_c$ and $φ_{_{\rm GS}}$ with in-plane magnetic field appear in junctions that are undoubtedly in trivial superconducting phase, raising concerns on the effectiveness of these probes in identifying topological transitions in planar junctions. We discuss possible strategies to confirm a topological superconducting phase in these platforms.
title Challenges in detecting topological superconducting transitions via supercurrent and phase probes in planar Josephson junctions
topic Superconductivity
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2307.11645