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Fermion-parity qubit in a proximitized double quantum dot

Geier, Max ; Souto, Rubén Seoane LU orcid ; Schulenborg, Jens ; Asaad, Serwan ; Leijnse, Martin LU and Flensberg, Karsten (2024) In Physical Review Research 6(2).
Abstract

Bound states in quantum dots coupled to superconductors can be in a coherent superposition of states with different electron number but with the same fermion parity. Electrostatic gating can tune this superposition to a sweet spot, where the quantum dot has the same mean electric charge independent of its electron-number parity. Here, we propose to encode quantum information in the local fermion parity of two tunnel-coupled quantum dots embedded in a Josephson junction. At the sweet spot, the qubit states have zero charge dipole moment. This protects the qubit from dephasing due to charge noise acting on the potential of each dot, as well as fluctuations of the (weak) interdot tunneling. At weak interdot tunneling, relaxation is... (More)

Bound states in quantum dots coupled to superconductors can be in a coherent superposition of states with different electron number but with the same fermion parity. Electrostatic gating can tune this superposition to a sweet spot, where the quantum dot has the same mean electric charge independent of its electron-number parity. Here, we propose to encode quantum information in the local fermion parity of two tunnel-coupled quantum dots embedded in a Josephson junction. At the sweet spot, the qubit states have zero charge dipole moment. This protects the qubit from dephasing due to charge noise acting on the potential of each dot, as well as fluctuations of the (weak) interdot tunneling. At weak interdot tunneling, relaxation is suppressed because of disjoint qubit states. However, for strong interdot tunneling the system is protected against noise affecting each quantum dot separately (energy-level noise, dot-superconductor tunneling fluctuations, and hyperfine interactions). Finally, we describe initialization and readout as well as single-qubit and two-qubit gates by pulsing gate voltages.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review Research
volume
6
issue
2
article number
023281
publisher
American Physical Society
external identifiers
  • scopus:85196425717
ISSN
2643-1564
DOI
10.1103/PhysRevResearch.6.023281
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
id
0db78285-c048-4270-8b63-a753e8572ba5
date added to LUP
2024-09-02 11:04:14
date last changed
2025-04-04 14:45:11
@article{0db78285-c048-4270-8b63-a753e8572ba5,
  abstract     = {{<p>Bound states in quantum dots coupled to superconductors can be in a coherent superposition of states with different electron number but with the same fermion parity. Electrostatic gating can tune this superposition to a sweet spot, where the quantum dot has the same mean electric charge independent of its electron-number parity. Here, we propose to encode quantum information in the local fermion parity of two tunnel-coupled quantum dots embedded in a Josephson junction. At the sweet spot, the qubit states have zero charge dipole moment. This protects the qubit from dephasing due to charge noise acting on the potential of each dot, as well as fluctuations of the (weak) interdot tunneling. At weak interdot tunneling, relaxation is suppressed because of disjoint qubit states. However, for strong interdot tunneling the system is protected against noise affecting each quantum dot separately (energy-level noise, dot-superconductor tunneling fluctuations, and hyperfine interactions). Finally, we describe initialization and readout as well as single-qubit and two-qubit gates by pulsing gate voltages.</p>}},
  author       = {{Geier, Max and Souto, Rubén Seoane and Schulenborg, Jens and Asaad, Serwan and Leijnse, Martin and Flensberg, Karsten}},
  issn         = {{2643-1564}},
  language     = {{eng}},
  number       = {{2}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review Research}},
  title        = {{Fermion-parity qubit in a proximitized double quantum dot}},
  url          = {{http://dx.doi.org/10.1103/PhysRevResearch.6.023281}},
  doi          = {{10.1103/PhysRevResearch.6.023281}},
  volume       = {{6}},
  year         = {{2024}},
}