We show how the superconducting phase difference in a Josephson junction may
be used to split the Kramers degeneracy of its energy levels and to remove all
the properties associated with time reversal symmetry. The superconducting
phase difference is known to be ineffective in two-terminal short Josephson
junctions, where irrespective of the junction structure the induced Kramers
degeneracy splitting is suppressed and the ground state fermion parity must
stay even, so that a protected zero-energy Andreev level crossing may never
appear. Our main result is that these limitations can be completely avoided by
using multi-terminal Josephson junctions. There the Kramers degeneracy breaking
becomes comparable to the superconducting gap, and applying phase differences
may cause the change of the ground state fermion parity from even to odd. We
prove that the necessary condition for the appearance of a fermion parity
switch is the presence of a "discrete vortex" in the junction: the situation
when the phases of the superconducting leads wind by $2\pi$. Our approach
offers new strategies for creation of Majorana bound states as well as spin
manipulation. Our proposal can be implemented using any low density, high
spin-orbit material such as InAs quantum wells, and can be detected using
standard tools.
Description
Single fermion manipulation via superconducting phase differences in multiterminal Josephson junctions
%0 Generic
%1 vanheck2014single
%A van Heck, B.
%A Mi, S.
%A Akhmerov, A. R.
%D 2014
%K graphene
%R 10.1103/PhysRevB.90.155450
%T Single fermion manipulation via superconducting phase differences in
multiterminal Josephson junctions
%U http://arxiv.org/abs/1408.1563
%X We show how the superconducting phase difference in a Josephson junction may
be used to split the Kramers degeneracy of its energy levels and to remove all
the properties associated with time reversal symmetry. The superconducting
phase difference is known to be ineffective in two-terminal short Josephson
junctions, where irrespective of the junction structure the induced Kramers
degeneracy splitting is suppressed and the ground state fermion parity must
stay even, so that a protected zero-energy Andreev level crossing may never
appear. Our main result is that these limitations can be completely avoided by
using multi-terminal Josephson junctions. There the Kramers degeneracy breaking
becomes comparable to the superconducting gap, and applying phase differences
may cause the change of the ground state fermion parity from even to odd. We
prove that the necessary condition for the appearance of a fermion parity
switch is the presence of a "discrete vortex" in the junction: the situation
when the phases of the superconducting leads wind by $2\pi$. Our approach
offers new strategies for creation of Majorana bound states as well as spin
manipulation. Our proposal can be implemented using any low density, high
spin-orbit material such as InAs quantum wells, and can be detected using
standard tools.
@misc{vanheck2014single,
abstract = {We show how the superconducting phase difference in a Josephson junction may
be used to split the Kramers degeneracy of its energy levels and to remove all
the properties associated with time reversal symmetry. The superconducting
phase difference is known to be ineffective in two-terminal short Josephson
junctions, where irrespective of the junction structure the induced Kramers
degeneracy splitting is suppressed and the ground state fermion parity must
stay even, so that a protected zero-energy Andreev level crossing may never
appear. Our main result is that these limitations can be completely avoided by
using multi-terminal Josephson junctions. There the Kramers degeneracy breaking
becomes comparable to the superconducting gap, and applying phase differences
may cause the change of the ground state fermion parity from even to odd. We
prove that the necessary condition for the appearance of a fermion parity
switch is the presence of a "discrete vortex" in the junction: the situation
when the phases of the superconducting leads wind by $2\pi$. Our approach
offers new strategies for creation of Majorana bound states as well as spin
manipulation. Our proposal can be implemented using any low density, high
spin-orbit material such as InAs quantum wells, and can be detected using
standard tools.},
added-at = {2019-06-29T16:22:16.000+0200},
author = {van Heck, B. and Mi, S. and Akhmerov, A. R.},
biburl = {https://www.bibsonomy.org/bibtex/23f4fa431aac3710a7d077e2907032901/cmcneile},
description = {Single fermion manipulation via superconducting phase differences in multiterminal Josephson junctions},
doi = {10.1103/PhysRevB.90.155450},
interhash = {c40656a50ff8d3c0bff33e13c78f1627},
intrahash = {3f4fa431aac3710a7d077e2907032901},
keywords = {graphene},
note = {cite arxiv:1408.1563Comment: Source code available as ancillary files. 10 pages, 7 figures. v2: minor changes, published version},
timestamp = {2019-06-29T16:22:16.000+0200},
title = {Single fermion manipulation via superconducting phase differences in
multiterminal Josephson junctions},
url = {http://arxiv.org/abs/1408.1563},
year = 2014
}