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1. 河北科技师范学院 物理系,河北 秦皇岛,066004
2. 内蒙古民族大学 物理与电子信息学院, 内蒙古 通辽 028043
3. 中国石油大学 化学工程学院 北京,102249
纸质出版日期:2017-4-5,
收稿日期:2016-11-8,
修回日期:2016-12-15,
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乌云其木格, 尹洪武, 苏都等. 计及厚度下量子点量子比特的电磁场依赖性[J]. 发光学报, 2017,38(4): 552-559
WUYUNQIMUGE, YIN Hong-wu, SU Du etc. Electromagnetic Field Dependence of Quantum Dot Qubit with The Thickness of Quantum Dot[J]. Chinese Journal of Luminescence, 2017,38(4): 552-559
乌云其木格, 尹洪武, 苏都等. 计及厚度下量子点量子比特的电磁场依赖性[J]. 发光学报, 2017,38(4): 552-559 DOI: 10.3788/fgxb20173804.0552.
WUYUNQIMUGE, YIN Hong-wu, SU Du etc. Electromagnetic Field Dependence of Quantum Dot Qubit with The Thickness of Quantum Dot[J]. Chinese Journal of Luminescence, 2017,38(4): 552-559 DOI: 10.3788/fgxb20173804.0552.
在电子-体纵光学(Longitudinal optical'LO)声子强耦合条件下'采用LLP-Pekar型变分法推导出计及厚度下量子点中极化子的基态和第一激发态能量本征值和本征函数以及平均声子数的电磁场依赖性。在此基础上'以极化子的二能级结构为载体构造了量子点量子比特。数值计算结果表明:量子比特的振荡周期
T
0
随量子点厚度
L
的增加而增大'随磁场的回旋频率
c
、电场强度
F
和电声子耦合强度
的增加而减小。量子比特的概率密度|
(
'z't
)|
2
随电子横向坐标
的变化呈现"正态分布"并受到量子盘厚度
L
和有效半径
R
0
的强烈影响'随电子纵向坐标
z
、角坐标
和时间
t
作周期性振荡变化。消相干时间
随磁场的回旋频率
c
、色散系数
和电子-声子耦合常数
的增加而增大'随电场强度
F
、量子点厚度
L
和有效半径
R
0
的增加而减小。量子点的厚度是量子点量子比特的一个重要参数'理论上可以通过设计不同的量子盘厚度并结合调节外加电磁场的强度'达到调控量子比特振荡周期、消相干时间大小的目的。
Based on the Lee-Low-Pines unitary transformation
the electromagnetic-field dependence of the eigenenergy
the eigenfunctions
and the mean number of phonons of both the ground-state and the first excited-state of the strong-coupling polaron in the quantum dot with the thickness were studied by using the Pekar variational method. On this basis
the quantum dot qubit was formed by means of the two-level structure of the polaron as the carrier. The results of numerical calculation indicate that the oscillation period
T
0
of the qubit increases with the increasing of the thickness
L
of the quantum disk
but decreases with the increasing of the cyclotron frequency
c
of the magnetic field
electric-field strength
F
and electron-phonon coupling strength
.The probability density |
(
z
t
)|
2
of the qubit presents the normal distribution with the variation of the electronic transverse coordinate
. It is significantly influenced by the thickness
L
and effective radius
R
0
of the quantum disk and shows the periodic oscillation with the variation of the electronic longitudinal coordinate
z
polar angle
and time
t
. The decoherence time
increases with the increasing of the cyclotron frequency
c
of the magnetic field
dispersion coefficient
and electron-phonon coupling strength
but decreases with the increasing of the electric-field strength
F
thickness
L
and effective radius
R
0
of the quantum disk. The thickness of the quantum dot is an important parameter of the qubit. Theoretically
the target of regulating the oscillation period
decoherence time and quality factor of the free rotation of the qubit can be achieved by designing the different thickness of the quantum disk and regulating the strength of the electromagnetic field.
量子点的厚度极化子量子比特电磁场依赖性
thickness of the quantum dotpolaronqubitelectromagnetic-field dependence
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