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1.
在Su-Schrieffer-Heeger (SSH)原子链中,电子在胞内和胞间的跳跃依赖于其自旋时,即SSH原子链存在自旋轨道耦合作用时,存在不同缠绕数的非平庸拓扑边缘态.如何探测自旋轨道耦合SSH原子链不同缠绕数的边缘态是一个重要问题.本文在紧束缚近似下研究了自旋轨道耦合SSH原子链的非平庸拓扑边缘态性质及其零能附近的电子输运特性.研究发现四重和二重简并边缘态的缠绕数分别为2和1;并且仅当源极入射电子的自旋被极化(铁磁电极)时,自旋轨道耦合SSH原子链在零能附近的电子输运特性才能反映其边缘态的能谱特性.尤其是,随着自旋轨道耦合SSH原子链与左、右导线之间的耦合强度由弱到强改变,对于缠绕数为2的四重简并边缘态,入射电子在零能附近的透射峰数目将从4个变为0;而对于缠绕数为1的二重简并边缘态情形,其透射峰数目将从2个变为0.因此,在源极为铁磁电极的情形下,通过观察自旋轨道耦合SSH原子链在零能附近电子共振透射峰的数目随着其与左、右导线之间耦合强度的变化,来探测其不同缠绕数的边缘态.上述结果为基于电子输运特性探测自旋轨道耦合SSH原子链不同拓扑性质的边缘态提供了一种可选择的理论方案.  相似文献   
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We quantify the nonclassicality of multimode bosonic field states by adopting an information-theoretic approach involving the Wigner-Yanase skew information. The fundamental properties of the quantifier such as convexity, superadditivity, monotonicity, and conservation relations are revealed. The quantifier is illustrated by a variety of typical examples, and applications to the quantification of nonclassical correlations are discussed. Various extensions are indicated.  相似文献   
4.
We reveal the electronic structure in Yb Cd2Sb2,a thermoelectric material,by angle-resolved photoemission spectroscopy(ARPES)and time-resolved ARPES(tr ARPES).Specifically,three bulk bands at the vicinity of the Fermi level are evidenced near the Brillouin zone center,consistent with the density functional theory(DFT)calculation.It is interesting that the spin-unpolarized bulk bands respond unexpectedly to right-and left-handed circularly polarized probe.In addition,a hole band of surface states,which is not sensitive to the polarization of the probe beam and is not expected from the DFT calculation,is identified.We find that the non-equilibrium quasiparticle recovery rate is much smaller in the surface states than that of the bulk states.Our results demonstrate that the surface states can be distinguished from the bulk ones from a view of time scale in the nonequilibrium physics.  相似文献   
5.
Min Zhong 《中国物理 B》2022,31(11):114201-114201
We propose a switchable vortex beam polarization state terahertz multi-layer metasurface, which consists of three-layer elliptical metal crosses, four-layer dielectrics, and two-layer hollow metal circles, which are alternately superimposed. Under the normal incidence of left-handed circularly polarized (LCP) wave and the right-handed circularly polarized (RCP) waves, the proposed structure realizes three independent control functions, i.e., focused and vortex beam, vortex beam with different topological charges, and polarization states switching, and azimuth switching of two vortex beams with different polarization states. The results show that the proposed metasurface provides a new idea for investigating the multifunctional terahertz wave modulation devices.  相似文献   
6.
The electronic structure of quantum dots (QDs) including band edges and possible trap states is an important physical property for optoelectronic applications. The reliable determination of the energy levels of QDs remains a big challenge. Herein we employ cyclic voltammetry (CV) to determine the energy levels of three types of ZnO QDs with different surface ligands. Coupled with spectroscopic techniques, it is found that the onset potential of the first reductive wave is likely related to the conduction band edges while the first oxidative wave originates from the trap states. The determined specific energy levels in CV further demonstrates that the ZnO QDs without surface ligands mainly have oxygen interstitial defects whilst the ZnO QDs covered with ligands contain oxygen vacancies. The present electrochemical method offers a powerful and effective way to determine the energy levels of wide bandgap ZnO QDs, which will boost their device performance.  相似文献   
7.
Transferring entangled states between matter qubits and microwave-field (or optical-field) qubits is of fundamental interest in quantum mechanics and necessary in hybrid quantum information processing and quantum communication. We here propose a way for transferring entangled states between superconducting qubits (matter qubits) and microwave-field qubits. This proposal is realized by a system consisting of multiple superconducting qutrits and microwave cavities. Here, „qutrit” refers to a three-level quantum system with the two lowest levels encoding a qubit while the third level acting as an auxiliary state. In contrast, the microwave-field qubits are encoded with coherent states of microwave cavities. Because the third energy level of each qutrit is not populated during the operation, decoherence from the higher energy levels is greatly suppressed. The entangled states can be deterministically transferred because measurement on the states is not needed. The operation time is independent of the number of superconducting qubits or microwave-field qubits. In addition, the architecture of the circuit system is quite simple because only a coupler qutrit and an auxiliary cavity are required. As an example, our numerical simulations show that high-fidelity transfer of entangled states from two superconducting qubits to two microwave-field qubits is feasible with present circuit QED technology. This proposal is quite general and can be extended to transfer entangled states between other matter qubits (e.g., atoms, quantum dots, and NV centers) and microwave- or optical-field qubits encoded with coherent states.  相似文献   
8.
《中国物理 B》2021,30(6):66701-066701
Floquet theorem is widely used in the light-driven systems. But many 2 D-materials models under the radiation are investigated with the high-frequency approximation, which may not be suitable for the practical experiment. In this work,we employ the non-perturbative Floquet method to strictly investigate the photo-induced topological phase transitions and edge states properties of graphene nanoribbons under the light irradiation of different frequencies(including both low and high frequencies). By analyzing the Floquet energy bands of ribbon and bulk graphene, we find the cause of the phase transitions and its relation with edge states. Besides, we also find the size effect of the graphene nanoribbon on the band gap and edge states in the presence of the light.  相似文献   
9.
本文采用基于多体格林函数方法和Bethe-Salpeter方程(GW/BSE)的电子结构计算方法和非绝热动力学模拟研究了两种不同桥连化学键构型(5-6构型和6-6构型)的酞菁锌-富勒烯(ZnPc-C60)给受体复合物的激发态性质及其弛豫过程. 对于6-6构型,ZnPc-C60的最低激发态S1态为光谱明态,即ZnPc的局域激发(LE)态,因此,6-6构型的ZnPc-C60在光激发之后几乎不会发生电荷分离过程. 相比之下,5-6构型的ZnPc-C60的S1态是C60的LE态,为光谱暗态,而作为光谱明态的ZnPc的LE态的能量更高. 而且,在ZnPc和C60的LE态之间还存在若干电荷转移(CT)态. 因此,电荷转移会在从高能的ZnPc的LE态到低能的C60的LE态的弛豫过程中发生. GW/BSE级别的非绝热动力学模拟结果进一步验证了电子结构计算的结论,并给出了相关过程的时间尺度:从ZnPc到C60的超快激发态能量转移过程在前200 fs完成;随后发生的是由C60到ZnPc的超快空穴转移过程. 本工作表明不同的桥连化学键模式(即5-6和6-6构型)可用于调节ZnPc-C60给体-受体复合物的激发态性质及其光电性质. 与此同时,本工作证明了GW/BSE级别的非绝热动力学方法是探索非周期性给体-受体复合物、有机金属配合物、量子点、纳米团簇等复杂体系的光诱导动力学的可靠工具.  相似文献   
10.
铒掺杂硼酸盐玻璃广泛应用于发光材料中,研究其发光动力学性质对于优化和提高其发光效率具有重要意义. 本文采用传统的熔融淬火法合成了摩尔比为2%的掺铒硼酸盐玻璃,并在低于硼酸盐玻璃转变温度(260 °C)下退火,退火处理后的掺铒硼酸盐玻璃光学性质得到了一定程度的提高. 硼酸盐玻璃未掺杂和掺杂Er3+的热性能采用差示扫描量热法以10 °C/min的速度进行测量. 同时还测量了掺铒硼酸盐玻璃发光机理的吸收光谱、激发光谱、稳态发射光谱、瞬态发射光谱和衰减动力学曲线. 实验结果表明Er3+在不同激发波长下556 nm处发射时具有不同的寿命,在掺铒硼酸盐玻璃中可能存在激发态阱,利用实验数据得到了激发态阱的深度为0.14 eV.  相似文献   
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