https://doi.org/10.1140/epjp/s13360-025-06156-9
Regular Article
Influence of impurity, thickness and bulk LO phonon on decoherence and Gaussian entropy of two-level system in a disk-shaped quantum dot under electric field
Institute of Condensed Matter Physics, Hebei Normal University of Science & Technology, 066004, Qinhuangdao, China
Received:
19
October
2024
Accepted:
19
February
2025
Published online:
18
March
2025
Using Pekar-type variational method, a qubit is constructed in a disk-shaped quantum dot (QD) by confined asymmetric Gaussian potential under electric field. The spontaneous emission rate of the bulk longitudinal optical (LO) phonons is studied based on the Lee-Low-Pines transformation and the Fermi golden rule, and then the qubit decoherence time and Gaussian entropy are discussed. The influence of the thickness of QD on Gaussian entropy is revealed for the first time. The numerical results show that Gaussian entropy show the characteristics of asymmetric “normal distribution” with the change of thickness of QD; The decoherence time and Gaussian entropy increases with the increase of electron–phonon coupling constant, dispersion coefficient and dielectric constant ratio, respectively; The decoherence time decreases with the increase of Gaussian potential well depth and electric field intensity, respectively; Gaussian entropy oscillates periodically with time. In addition, it is found that asymmetric Gaussian potential well depth, thickness of QD, dielectric constant ratio and electric field have significant potential to regulate Gaussian entropy and decoherence: When the thickness of the QD is 
, the “abrupt change” of decoherence time from increasing to decreasing with the increase of dielectric constant ratio is observed; A maximum value (peak value) of Gaussian entropy is observed near the thickness 
and some minimum values (valley value) distribution of qubit decoherence time are discovered in the thickness interval 
; In the asymmetric Gaussian potential well depth interval 
, it is found that the Gaussian entropy occurs a “transition” from increasing with the increase of electric field intensity to decreasing. The conclusion of this paper will provide a theoretical basis for the experimental scheme to regulate the different characteristics of QD carrier such as the dispersion coefficient, electron–phonon coupling constant, dielectric constant ratio and electric field.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
