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Quantum dot; qubit; probability density; oscillation period; decoherence time; dispersion.

Selecting the asymmetric Gaussian (AG) potential to describe the confinement of electron in a disk-shaped quantum dot (QD), the ground state and the first excited state energy and wave function of the system are derived by using the Lee–Low–Pines (LLP) Pekar transformation variational method, and the two-level structure required for a qubit is constructed. The influence of material parameters such as the dispersion coefficient, dielectric constant ratio and electron–phonon coupling constant on the qubit properties of AG potential QD with the electromagnetic field are investigated. The results show that the electric field and magnetic field have opposite adjustment functions for the formation of qubit. The electric field is advantageous for the qubit survival and information storage, while magnetic field and electron–phonon coupling are detrimental to the qubit survival and information storage, respectively. The decoherence time of the qubit increases with increasing magnetic field cyclotron frequency ‘from the turning point’. Applying an electric field, increasing the dielectric constant ratio, the dispersion coefficient and the electron–phonon coupling constant of the materials are all beneficial to improve the coherence of the qubit.

WUYUNQIMUGE ¹ WEI XIN² LIU XIAO-XU² EERDUNCHAOLU ²

1. College of Mathematics and Physics, Inner Mongolia University for Nationalities, Tongliao 028043, China
2. Department of Physic, Hebei Normal University of Science and Technology, Qinhuangdao 066004, China

Published

10 July 2020

Manuscript received

25 September 2019

Manuscript revised

3 March 2020

Accepted

9 April 2020