2007/12/11 by A. Kwasniowski, A Kwaśniowski, J. Adamowski
Physics and Astronomy · #Condensed matter physics #Electron #Exchange interaction #Excited state #Exponential function #Molecular physics #Physics #Potential energy #Quantum and electron transport phenomena #Quantum dot #Quantum mechanics #Quantum tunnelling #Semiconductor Quantum Structures and Devices #Singlet state #Surface and Thin Film Phenomena #cond-mat.mes-hall
paper · pdf · doi:10.1088/0953-8984/20/21/215208
16 pages, including 11 figures
arxiv created 2007/12/11 · openalex publication_date 2008/04/18 · arxiv updated 2015/05/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Exchange interaction has been studied for electrons in coupled quantum dots (QDs) by a configuration interaction method using confinement potentials with different profiles. The confinement potential has been parametrized by a two-centre power-exponential function, which allows us to investigate various types of QDs described by either soft or hard potentials of different ranges. For the soft (Gaussian) confinement potential the exchange energy decreases with increasing interdot distance due to the decreasing interdot tunnelling. For the hard (rectangular-like) confinement potential we have found a non-monotonic behaviour of the exchange interaction as a function of distance between the confinement potential centres. In this case, the exchange interaction energy exhibits a pronounced maximum for the confinement potential profile which corresponds to the nanostructure composed of the small inner QD with a deep potential well embedded in the large outer QD with a shallow potential well. This effect results from the strong localization of electrons in the inner QD, which leads to the large singlet–triplet splitting. Implications of this finding for quantum logic operations have been discussed.