采用Lee-Low-Pines变换和Pekar类型变分法推导出非对称高斯势施主中心量子点中束缚极化子的基态和激发态能量和波函数, 进而构造了一量子比特所需的二能级结构。基于费米黄金规则和偶级近似研究了束缚极化子基态的衰变。引入了一个用两态极化子基态衰变时间来量化量子点量子比特退相干时间的量度法, 并与极化子激发态衰变时间量化量子点量子比特退相干度量法进行了对照讨论, 揭示了二者的相同物理机理。通过研究电场下材料的介电常数比、电声耦合常数和温度对施主中心量子点中束缚极化子基态寿命的影响, 揭示了材料属性与环境因素对量子点量子比特退相干的影响。

The ground-state and excited-state energy and wave function of polaron in donor-center quantum dot with asymmetric Gaussian potential are derived by Lee-Low-Pines transformation and Pekar-type variational method, and then the two-level structure for a qubit is constructed. The measure of qubit decoherence time of quantum dots quantified by ground state decay time of two-state polaron is established, which is compared with the measure of qubit decoherence time of quantum dots quantified by polaron excited state decay time. And their physical mechanism is revealed. By studying the influence of dielectric constant ratio, electron-phonons coupling constant, temperature and electric field on the ground-state lifetime of bound polaron in the donor-center quantum dot with asymmetric Gaussian potential, the influence of material properties, temperature, electric field and other environmental factors on qubit decoherence of quantum dots is revealed.