Abstract

The number of electrons in small metallic or semiconducting islands is quantised. When tunnelling is enabled via opaque barriers this number can change by an integer. In superconductors the addition is in units of two electron charges (2e), reflecting that the Cooper pair condensate must have an even parity. This ground state (GS) is foundational for all superconducting qubit devices. Here, we study a hybrid superconducting–semiconducting island and find three typical GS evolutions in a parallel magnetic field: a robust 2e-periodic even-parity GS, a transition to a 2e-periodic odd-parity GS, and a transition from a 2e- to a 1e-periodic GS. The 2e-periodic odd-parity GS persistent in gate-voltage occurs when a spin-resolved subgap state crosses zero energy. For our 1e-periodic GSs we explicitly show the origin being a single zero-energy state gapped from the continuum, i.e., compatible with an Andreev bound states stabilized at zero energy or the presence of Majorana zero modes.

Details

Title
Parity transitions in the superconducting ground state of hybrid InSb–Al Coulomb islands
Author
Shen, Jie 1 ; Heedt, Sebastian 1 ; Borsoi, Francesco 1 ; Bernard van Heck 2   VIAFID ORCID Logo  ; Gazibegovic, Sasa 3 ; Roy L M Op het Veld 3 ; Car, Diana 3 ; Logan, John A 4   VIAFID ORCID Logo  ; Pendharkar, Mihir 5   VIAFID ORCID Logo  ; Ramakers, Senja J J 1 ; Wang, Guanzhong 1 ; Xu, Di 1   VIAFID ORCID Logo  ; Bouman, Daniël 1   VIAFID ORCID Logo  ; Geresdi, Attila 1   VIAFID ORCID Logo  ; Palmstrøm, Chris J 6 ; Erik P A M Bakkers 3   VIAFID ORCID Logo  ; Kouwenhoven, Leo P 7 

 QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands 
 Microsoft Quantum, Microsoft Station Q, University of California Santa Barbara, Santa Barbara, CA, USA 
 QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands; Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands 
 Materials Department, University of California Santa Barbara, Santa Barbara, CA, USA 
 Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, USA 
 Materials Department, University of California Santa Barbara, Santa Barbara, CA, USA; Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, USA 
 QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands; Microsoft Station Q at Delft University of Technology, Delft, The Netherlands 
Pages
1-8
Publication year
2018
Publication date
Nov 2018
Publisher
Nature Publishing Group
e-ISSN
20411723
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2133834096
Copyright
© 2018. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.