Signatures of topological phase transitions in mesoscopic superconducting rings
We investigate Josephson currents in mesoscopic rings with a weak link which are in or near a topological superconducting phase. As a paradigmatic example, we consider the Kitaev model of a spinless p-wave superconductor in one dimension, emphasizing how this model emerges from more realistic settin...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2013-01-01
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| Series: | New Journal of Physics |
| Online Access: | https://doi.org/10.1088/1367-2630/15/2/025001 |
| _version_ | 1797751737715523584 |
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| author | Falko Pientka Alessandro Romito Mathias Duckheim Yuval Oreg Felix von Oppen |
| author_facet | Falko Pientka Alessandro Romito Mathias Duckheim Yuval Oreg Felix von Oppen |
| author_sort | Falko Pientka |
| collection | DOAJ |
| description | We investigate Josephson currents in mesoscopic rings with a weak link which are in or near a topological superconducting phase. As a paradigmatic example, we consider the Kitaev model of a spinless p-wave superconductor in one dimension, emphasizing how this model emerges from more realistic settings based on semiconductor nanowires. We show that the flux periodicity of the Josephson current provides signatures of the topological phase transition and the emergence of Majorana fermions (MF) situated on both sides of the weak link even when fermion parity is not a good quantum number. In large rings, the MF hybridize only across the weak link. In this case, the Josephson current is h / e periodic in the flux threading the loop when fermion parity is a good quantum number but reverts to the more conventional h /2 e periodicity in the presence of fermion-parity changing relaxation processes. In mesoscopic rings, the MF also hybridize through their overlap in the interior of the superconducting ring. We find that in the topological superconducting phase, this gives rise to an h / e -periodic contribution even when fermion parity is not conserved and that this contribution exhibits a peak near the topological phase transition. This signature of the topological phase transition is robust to the effects of disorder. As a byproduct, we find that close to the topological phase transition, disorder drives the system deeper into the topological phase. This is in stark contrast to the known behavior far from the phase transition, where disorder tends to suppress the topological phase. |
| first_indexed | 2024-03-12T16:53:58Z |
| format | Article |
| id | doaj.art-bfcb28aedff1494b948ec8606aba94c1 |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:53:58Z |
| publishDate | 2013-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-bfcb28aedff1494b948ec8606aba94c12023-08-08T11:04:45ZengIOP PublishingNew Journal of Physics1367-26302013-01-0115202500110.1088/1367-2630/15/2/025001Signatures of topological phase transitions in mesoscopic superconducting ringsFalko Pientka0Alessandro Romito1Mathias Duckheim2Yuval Oreg3Felix von Oppen4Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin , D-14195 Berlin, GermanyDahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin , D-14195 Berlin, GermanyDahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin , D-14195 Berlin, GermanyDepartment of Condensed Matter Physics, Weizmann Institute of Science , Rehovot 76100, IsraelDahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin , D-14195 Berlin, GermanyWe investigate Josephson currents in mesoscopic rings with a weak link which are in or near a topological superconducting phase. As a paradigmatic example, we consider the Kitaev model of a spinless p-wave superconductor in one dimension, emphasizing how this model emerges from more realistic settings based on semiconductor nanowires. We show that the flux periodicity of the Josephson current provides signatures of the topological phase transition and the emergence of Majorana fermions (MF) situated on both sides of the weak link even when fermion parity is not a good quantum number. In large rings, the MF hybridize only across the weak link. In this case, the Josephson current is h / e periodic in the flux threading the loop when fermion parity is a good quantum number but reverts to the more conventional h /2 e periodicity in the presence of fermion-parity changing relaxation processes. In mesoscopic rings, the MF also hybridize through their overlap in the interior of the superconducting ring. We find that in the topological superconducting phase, this gives rise to an h / e -periodic contribution even when fermion parity is not conserved and that this contribution exhibits a peak near the topological phase transition. This signature of the topological phase transition is robust to the effects of disorder. As a byproduct, we find that close to the topological phase transition, disorder drives the system deeper into the topological phase. This is in stark contrast to the known behavior far from the phase transition, where disorder tends to suppress the topological phase.https://doi.org/10.1088/1367-2630/15/2/025001 |
| spellingShingle | Falko Pientka Alessandro Romito Mathias Duckheim Yuval Oreg Felix von Oppen Signatures of topological phase transitions in mesoscopic superconducting rings New Journal of Physics |
| title | Signatures of topological phase transitions in mesoscopic superconducting rings |
| title_full | Signatures of topological phase transitions in mesoscopic superconducting rings |
| title_fullStr | Signatures of topological phase transitions in mesoscopic superconducting rings |
| title_full_unstemmed | Signatures of topological phase transitions in mesoscopic superconducting rings |
| title_short | Signatures of topological phase transitions in mesoscopic superconducting rings |
| title_sort | signatures of topological phase transitions in mesoscopic superconducting rings |
| url | https://doi.org/10.1088/1367-2630/15/2/025001 |
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