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11.
Dynamic Localization Condition of Two Electrons in a Strong dc-ac Biased Quantum Dot Molecule
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We present a perturbation investigation of dynamic localization condition of two electrons in a strong dc-ac biased quantum dot molecule.By reducing the system to an Hubbard-type effective two-site model and by applying Floquet theory,we find that the dynamical localization phenomenon occurs under certain values of the large strength of the dc and ac field.This demonstrates the possibility of using appropriate dc-ac fields to manipulate dynamical localized states in mesoscopic devices,which is an essential component of practical schemesfor quantum information processing.Our conclusion is instructive to the field of quantum function devices. 相似文献
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13.
Intrinsic Hall effect and separation of Rashba and Dresselhaus spin splittings in semiconductor quantum wells
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We have proposed a method to separate Rashba and Dresselhaus spin splittings in
semiconductor quantum wells by using the intrinsic Hall effect. It is shown that the
interference between Rashba and Dresselhaus terms can deflect the electrons in
opposite transverse directions with a change of sign in the macroscopic Hall
current, thus providing an alternative way to determine the different contributions
to the spin--orbit coupling. 相似文献
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15.
对原子氢在Be(1010)薄膜表面的吸附性质做了第一性原理计算研究.根据原子面间距的不同,可把Be(1010)表面分为两种.计算结果表明,原子氢在这两种表面上的吸附性质显著不同.为阐明和分析这些不同,系统计算和分析了Be(1010)薄膜的表面电子结构、电子功函数、平均静电势和局域电荷密度.这些物理量都自洽地表明,吸附过程中原子氢和表面铍原子间的电荷转移过程对于两种表面是完全不同的.对于L型表面来说,电荷由吸附原子氢向表面Be原子层转移,而对于S型表面而言,电荷转移过程恰恰相反. 相似文献
16.
Effects of bias on dynamics of an AC-driven two-electron quantum-dot molecule 总被引:1,自引:0,他引:1
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The effects of bias on the dynamical localization of two interacting electrons in a pair of coupled quantum dots driven by external AC fields have been numerically investigated. With an effective two-site model and Floquet formalism,the time-dependent Schroedinger equation is numerically solved and the Pmin, the minimum of the population evolution of the initial state within a certain time period, is used to quantify the degree of the dynamical localization. Results indicate that the bias can change the energy of the initial state and break the dynamical symmetry of the system with a pure AC field. And the amplitude of the AC field with dynamical localization phenomenon changes with bias. All the numerical results are explained by the perturbation theory and two-level approximation. 相似文献
17.
本文讨论了荷电费米子与固定狄拉克双荷子相互作用系统的束缚态,给出了最低角动量j=|q|-1/2≥0和总角动量j≥|q|+1/2的全部能级的表达式,结果表明,系统能级对所有角量子数j≥|q|-1/2≥0都是简并的,这意味着引入额外磁矩项和相互作用项修正后的哈密顿量的对称性有了明显的提高。 相似文献
18.
Quantum-state engineering, i.e. active manipulation over the coherent dynamics of
suitable quantum-mechanical systems, has become a fascinating prospect of modern
physics. Here we discuss the dynamics of two interacting electrons in a coupled
quantum dot driven by an external electric field. The results show that the two
quantum dots can be used to prepare a maximally entangled Bell state by changing
the strength and duration of an oscillatory electric field. Different from the
suggestion made by Loss \textit et al (1998 Phys. Rev. A 57 120, the
present entanglement involves the spatial degree of freedom for the two electrons.
We also find that the coherent tunnelling suppression discussed by Grossmann
\textit et al (1991 Phys. Rev. Lett. 67 516 persists in the
two-particle case: i.e. two electrons initially localized in one dot can remain
dynamically localized, although the strong Coulomb repulsion prevents them from
behaving so. Surprisingly, the interaction enhances the degree of localization to a
large extent compared with that in the non-interacting case. This phenomenon is
referred to as the Coulomb-enhanced dynamical localization. 相似文献
19.
By the numerical method, we show a transition process from static to dynamic electric-field domain formation in semiconductor superlattices. During this transition, there can be noticed a sawtooth-like zone in which static and dynamic electric-field domain zones appear alternatively with increasing voltage. Therefore, a dynamic dc voltage band emerges from each sawtooth-like branch of the current-voltage characteristic. These results are qualitatively in agreement with experiment. 相似文献
20.
Within the framework of effective mass approximation, we have calculated the electronic structure of the two laterally coupled quantum dots with a donor by the finite element method. The calculated results show that the bond states of quantum-dot molecules are quite sensitive to the donor positions. By varying the donor position, the transition from covalent to ionic bond state is realized for some electronic states. Some extreme cases are also discussed for comparison. 相似文献