非对称量子点中极化子的声子平均数

采用线性组合算符和幺正变换方法研究非对称量子点中强、弱耦合极化子的声子平均数的性质,导出了量子点中强、弱耦合极化子的声子平均数和振动频率随量子点的横向和纵向受限强度、电子-声子耦合强度的变化关系。对RbCl晶体进行数值计算,结果表明非对称量子点中强耦合极化子的振动频率和声子平均数随量子点的横向和纵向的受限强度的增强而迅速增大,随电子-声子耦合强度的增强而增大。

Mean Number of Phonons for Polaron in an Asymmetric Quantum Dot

In the early 1980's, Tokuda investigated the mean number of phonons in the cloud around the electron for both the optical and the piezoelectric polarons within the scheme of variational approach based on the unitary transformation and the method of the Lagrange multiplier. Many investigators studied the properties of the mean number of phonons of polaron by many other methods. Recently, the properties of the mean number of phonons of the polaron and the bound magnetopolaron in a symmetric quantum dot have been studied using the linear-combination operator and unitary transformation method by one of the present authors and co-worker. However, using linear-combination operator method, the properties of the mean number of phonons for polaron in an asymmetric quantum dot has not been investigated so far. In this paper, the influences the asymmetric parabolic confined potential on the properties of the mean number of phonons for the polaron in quantum dot are studied by using linear-combination operator and the unitary transformation method. The relations between the mean number of phonons and the vibrational frequency of the strong- and weak-coupling polaron in an asymmetric quantum dot with the transverse and longitudinal direction confinement strength of the quantum dot and the electron-phonon coupling strength are derived. Numerical calculations on the RbCl crystal, as an example, are performed, and the results show that the mean number of phonons and the vibrational frequency of the strong-coupling polaron will increase strongly with increasing the transverse and longitudinal confinement strength of the quantum dot. The mean number of phonons and the vibrational frequency of the strong-coupling polaron will increase with increasing the electron-phonon coupling strength.