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Portrait of Martin Leijnse; Photo: Kennet Ruona

Martin Leijnse

Professor, Member of NanoLund Management Group

Portrait of Martin Leijnse; Photo: Kennet Ruona

Quantum interference in transport through almost symmetric double quantum dots

Author

  • Zeng Zhao Li
  • Martin Leijnse

Summary, in English

We theoretically investigate transport signatures of quantum interference in highly symmetric double quantum dots in a parallel geometry and demonstrate that extremely weak symmetry-breaking effects can have a dramatic influence on the current. Our calculations are based on a master equation in which quantum interference enters as nondiagonal elements of the density matrix of the double quantum dots. We also show that many results have a physically intuitive meaning when recasting our equations as Bloch-like equations for a pseudospin associated with the dot occupation. In the perfectly symmetric configuration with equal tunnel couplings and orbital energies of both dots, there is no unique stationary-state density matrix. Interestingly, however, adding arbitrarily small symmetry-breaking terms to the tunnel couplings or orbital energies stabilizes a stationary state either with or without quantum interference, depending on the competition between these two perturbations. The different solutions can correspond to very different current levels. Therefore, if the orbital energies and/or tunnel couplings are controlled by, e.g., electrostatic gating, the double quantum dot can act as an exceptionally sensitive electric switch.

Department/s

  • Solid State Physics
  • NanoLund: Center for Nanoscience

Publishing year

2019

Language

English

Publication/Series

Physical Review B

Volume

99

Issue

12

Document type

Journal article

Publisher

American Physical Society

Topic

  • Condensed Matter Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 2469-9950