抛物势量子点中强耦合双极化子量子比特的性质

Properties of Strong-coupling Bipolaron Qubit in Parabolic Potential Quantum Dot

基于LLP幺正变换,采用Pekar型变分法得到了二维量子点中强耦合双极化子的基态和第一激发态的能量和波函数,进而构造了一个双极化子的量子比特。数值结果表明:在量子比特内,两电子的空间几率密度的时间振荡周期T0随电声子耦合强度α、量子点的受限强度ω0以及介质的介电常数比η的增加而减小;在量子比特内,两电子的空间几率密度Q随时间t、角坐标φ2及介电常数比η的变化而作周期性振荡;两电子在量子点中心附近区域出现的几率较大,而在远离量子点中心区域出现的几率很小。

On the basis of Lee-Low-Pines （LLP） unitary transformation, the eigenenergy and eigen- function of the ground-state and the first excited state of the strong-coupling bipolaron in two-dimensional quantum dot （QD） were obtained by using the variational method of Pekar type. A qubit was formed by overlaying both the ground state and the first excited state of the bipolaron system. Numerical calculations indicate that the oscillating period To of qubits decreases with the increasing the electron-phonon coupling strength a, the confinement strength too of the quantum dot, and the dielectric constant ratio η; the distribution of the probability density Q of the electrons in quantum dot oscillates periodically with time t, angle coordinate φ2, and the dielectric constant ratio η, and there is a maximum at near the center and zero away from the center of quantum dot.