抛物势量子点中强耦合双极化子量子比特的性质

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。

量子棒中强耦合磁极化子基态能量的磁场和温度依赖性

基于Huybrechts-Lee-Low-Pines变分法,研究量子棒中强耦合磁极化子基态能量的磁场和温度依赖性。结果表明:磁极化子基态能量的绝对值随温度参数的增加而增大,随电子-声子耦合强度的增加而增大,随磁场的回旋频率的增加而减小,随量子棒受限强度的增加而减小;磁极化子的基态能量随量子棒纵横比的变化规律呈'√'型曲线,并受到温度的显著影响。

磁场和LO声子效应对量子盘中强耦合磁极化子qubit的影响

采用Lee-Low-Pines-Huybrechts变分法研究了外磁场、LO声子效应和量子点厚度对量子盘中电子-LO声子强耦合磁极化子的振动频率和qubit的影响,推导出磁极化子的振动频率λ,量子比特振荡的周期T0和电子的几率分布ρ的表达式。数值计算结果表明,磁极化子基态的振动频率大于激发态的振动频率,λ随ωc和α的增加而增大,随L的增加而减小;T0随受限强度ω0和量子盘厚度L的增加而增大,随电子-声子耦合强度α的增加而减小;ρ随ω0的增加而减小,随L的增加而振荡减小;T0和ρ随ωc和L的变化规律受ω0和α的影响显著。

Properties of strong-coupling magneto-bipolaron qubit in quantum dot under magnetic field

Based on the variational method of Pekar type, we study the energies and the wave-functions of the ground and the first-excited states of magneto-bipolaron, which is strongly coupled to the LO phonon in a parabolic potential quantum dot under an applied magnetic field, thus built up a quantum dot magneto-bipolaron qubit. The results show that the oscillation period of the probability density of the two electrons in the qubit decreases with increasing electron–phonon coupling strength α, resonant frequency of the magnetic field ωc, confinement strength of the quantum dot ω0, and dielectric constant ratio of the medium η; the probability density of the two electrons in the qubit oscillates periodically with increasing time t, angular coordinate φ2, and dielectric constant ratio of the medium η; the probability of electron appearing near the center of the quantum dot is larger, and the probability of electron appearing away from the center of the quantum dot is much smaller.

Ground and Excited States of Bipolarons in Two and Three Dimensions

The properties of large bipolarons in two and three dimensions are investigated by averaging over therelative wavefunction of the two electrons and using the Lee-Low-Pines-Huybrechts variational method.The ground-state(GS)and excited-state energies of the Frhlich bipolaron for the whole range of electron-phonon coupling constantscan be obtained.The energies of the first relaxed excited state(RES)and Franck-Condon(FC)excited state of thebipolaron are also calculated.It is found that the first RES energy is lower than the FC state energy.The comparisonof our GS and RES energies with those in literature is also given.

抛物量子点中强耦合双极化子的有效势

基于Lee-Low-Pines-Huybrechts变分方法研究了抛物量子点中强耦合双极化子的基态性质,并推导出了量子点中强耦合双极化子有效势Veff随电子-声子耦合强度α、两电子相对距离r和量子点半径R0的变化规律。结果表明,有效势Veff由库仑势Vcoul、量子点的限定势Vconf和诱生势Ve-LO三部分组成;其中诱生势Ve-LO总是小于零,其绝对值Ve-LO随电子-声子耦合强度α的增加而增大,随电子间相对距离r和量子点半径R0的减小而增大。双极化子有效势的绝对值Veff随电子-声子耦合强度α的增加而增大,随电子间相对距离r的减小而增大。耦合强度α和电子间相对距离r是影响有效势Veff的主要因素,而量子点半径R0和介电常数比η对有效势Veff的影响较小。

量子棒中弱耦合极化子有效质量的温度依赖性

基于Tokuda-Lee-Low-Pines变分法研究了温度对非均匀抛物限制势下量子棒中弱耦合极化子有效质量的影响,推导出量子棒中弱耦合极化子的有效质量m*随量子棒纵横比e′、电子-声子耦合强度α和温度参数γ的变化规律。数值计算结果表明,量子棒中弱耦合极化子的横向有效质量m‖*和纵向有效质量mz*均随电子-声子耦合强度α的增加而增大,随温度T的升高而减小;量子棒中极化子的横向有效质量m‖*随量子棒纵横比e′的增加而增大,纵向有效质量mz*随e′的增加而减小。