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。

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。