Fermion parity and quantum capacitance oscillation with partially separated Majorana and quasi-Majorana modes

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Hauptverfasser: Stanescu, Tudor D., Tewari, Sumanta
Format: Preprint
Veröffentlicht: 2025
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author Stanescu, Tudor D.
Tewari, Sumanta
author_facet Stanescu, Tudor D.
Tewari, Sumanta
contents In a recent experiment, flux dependent oscillations of the quantum capacitance were observed in a one dimensional spin-orbit coupled semiconductor superconductor heterostructure connected end to end via a quantum dot and threaded by a magnetic flux. In the topological superconducting phase of the heterostructure, the oscillations corresponding to different fermion parity sectors are shifted by half a period and can serve as a mechanism for fermion parity readout or fusion operations involving a pair of localized, well separated Majorana modes. In this work, we demonstrate that flux induced fermion parity dependent oscillations of the quantum capacitance in a disordered semiconductor superconductor quantum dot system can originate not only from topologically protected, spatially well separated Majorana zero modes (MZMs) localized at the wire ends, but also, generically, from partially separated Majorana modes with significant overlap, as well as from quasi-Majorana modes in the topologically trivial phase, which can be viewed as Andreev bound states whose constituent Majorana wave functions are slightly shifted relative to each other and have nonzero amplitude at opposite ends of the wire. Therefore, while the detection of flux dependent oscillations of quantum capacitance marks an important experimental advance, such observations alone do not constitute evidence of the presence of topological Majorana zero modes.
format Preprint
id arxiv_https___arxiv_org_abs_2505_23741
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Fermion parity and quantum capacitance oscillation with partially separated Majorana and quasi-Majorana modes
Stanescu, Tudor D.
Tewari, Sumanta
Mesoscale and Nanoscale Physics
Quantum Physics
In a recent experiment, flux dependent oscillations of the quantum capacitance were observed in a one dimensional spin-orbit coupled semiconductor superconductor heterostructure connected end to end via a quantum dot and threaded by a magnetic flux. In the topological superconducting phase of the heterostructure, the oscillations corresponding to different fermion parity sectors are shifted by half a period and can serve as a mechanism for fermion parity readout or fusion operations involving a pair of localized, well separated Majorana modes. In this work, we demonstrate that flux induced fermion parity dependent oscillations of the quantum capacitance in a disordered semiconductor superconductor quantum dot system can originate not only from topologically protected, spatially well separated Majorana zero modes (MZMs) localized at the wire ends, but also, generically, from partially separated Majorana modes with significant overlap, as well as from quasi-Majorana modes in the topologically trivial phase, which can be viewed as Andreev bound states whose constituent Majorana wave functions are slightly shifted relative to each other and have nonzero amplitude at opposite ends of the wire. Therefore, while the detection of flux dependent oscillations of quantum capacitance marks an important experimental advance, such observations alone do not constitute evidence of the presence of topological Majorana zero modes.
title Fermion parity and quantum capacitance oscillation with partially separated Majorana and quasi-Majorana modes
topic Mesoscale and Nanoscale Physics
Quantum Physics
url https://arxiv.org/abs/2505.23741