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.
Volume 94, 2020
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