共查询到20条相似文献,搜索用时 31 毫秒
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A. Kanshu C. E. Rüter D. Kip V. M. Shandarov 《Applied physics. B, Lasers and optics》2009,95(3):537-543
Formation of defect states by optical induction in one-dimensional photonic lattices fabricated in photorefractive lithium
niobate is investigated experimentally. First, by using a moving narrow laser beam for defect recording, we investigate light
propagation in samples containing single line defects and adjacent channel defects forming directional couplers. Then, these
results are used to create lattices with randomly distributed defects, resembling a disordered optical potential. In such
lattices, wave propagation is found to change from ballistic transport to transverse Anderson-like light localization as a
function of induced disorder. 相似文献
3.
We study the heat current J in a classical one-dimensional disordered chain with on-site pinning and with ends connected to stochastic thermal reservoirs at different temperatures. In the absence of anharmonicity all modes are localized and there is a gap in the spectrum. Consequently J decays exponentially with system size N. Using simulations we find that even a small amount of anharmonicity leads to a J approximately 1/N dependence, implying diffusive transport of energy. 相似文献
4.
在单电子紧束缚无序模型基础上,建立了一维二元非对角关联无序体系电子跳跃输运交流电导模型,并推导了其交流电导公式,通过计算其交流电导率,探讨了格点能量无序度、格点原子组分、非对角关联及温度、外场对体系交流跳跃电导的影响.计算结果表明,一维二元非对角关联无序体系的交流电导率随格点能量无序度的增大而减小.同时,体系中两种原子的组分的变化实际代表着体系成分无序程度的变化,因而对其交流电导率的影响很大,表现为随A类原子含量p的增加而先减小后增大.当引入非对角关联时,体系出现退局域化现象,电子波函数由局
关键词:
二元无序体系
交流跳跃电导
格点能量无序度
非对角关联 相似文献
5.
The propagation of surface plasmon polaritons in dielectric loaded waveguides with randomly placed scatterers is studied using both numerical simulations and a simplified transfer matrix framework. Despite the importance of losses in this system, we find fingerprints of the localized behavior of one-dimensional disordered systems. Furthermore, losses amplify the impact of the necklace states on the transport properties for systems not much larger than the localization length. The system presented here also offers the possibility to use localization effects for engineering purposes by means of deliberately introduced disorder. 相似文献
6.
Localization length of wave functions in one-dimensional disordered systems with periodic modulation
《Solid State Communications》1987,62(2):69-71
The localization length of wave functions in one-dimensional disordered systems with periodic modulation is studied. The role of spatial inhomogeneity in the problem is considered. We calculate the localization length varying with energy for the compositionally modulated systems with either the disorder of Anderson distributions or the randomness of periods. The results show that the non-uniformity of disordered systems leads to some different properties of the localized wave functions. 相似文献
7.
We analytically compute a localization criterion in the double-scattering approximation for a set of dielectric spheres or perfectly conducting discs uniformly distributed in a spatial volume which may be either spherical or layered. For every disordered medium, we numerically investigate a localization criterion and examine the influence of the system parameters on the wavelength localization domains. 相似文献
8.
The effect of a continuous model of correlations upon
one-dimensional finite disordered quantum wires modeled by an array of
delta-potentials, is analyzed. Although the model proposed is not able to
include new truly extended states in the spectrum, the transport properties
of a finite sample are noticeably improved due to the existence of states
whose localization length is larger than the system size. This
enhancement of transmission is maximized for relatively short chains. 相似文献
9.
《Nuclear Physics B》1998,532(3):689-732
We study the diffusive motion of low-energy normal quasiparticles along the core of a single vortex in a dirty, type-II, s-wave superconductor. The physics of this system is argued to be described by a one-dimensional supersymmetric non-linear σ model, which differs from the σ models known for disordered metallic wires. For an isolated vortex and quasiparticle energies less than the Thouless energy ETh, we recover the spectral correlations that are predicted by random matrix theory for the universality class C. We then consider the transport problem of transmission of quasiparticles through a vortex connected to particle reservoirs at both ends. The transmittance at zero energy exhibits a weak localization correction reminiscent of quasi-one-dimensional metallic systems with symmetry index β = 1. Weak localization disappears with increasing energy over a scale set by ETh This crossover should be observable in measurements of the longitudinal heat conductivity of an ensemble of vortices under mesoscopic conditions. In the regime of strong localization, the localization length is shown to decrease by a factor of 8 as the quasiparticle energy goes to zero. 相似文献
10.
We propose a novel scheme to trap a particle based on a delicate interplay between coherence and decoherence. If the decoherence occurs as a particle is located in the scattering region and subsequently the appropriate destructive interference takes place, the particle can be trapped in the scattering area. We consider two possible experimental realizations of such trapping: a ring attached to a single lead and a ring attached to two leads. Our scheme has nothing to do with a quasi-bound state of the system, but has a close analogy with the weak localization phenomena in disordered conductors. 相似文献
11.
We study the transport properties of interacting electrons in a disordered quantum wire within the framework of the Luttinger liquid model. The conductivity at finite temperature is nonzero only because of inelastic electron-electron scattering. We demonstrate that the notion of weak localization is applicable to the strongly correlated one-dimensional electron system. We calculate the relevant dephasing rate, which for spinless electrons is governed by the interplay of electron-electron interaction and disorder, thus vanishing in the clean limit. 相似文献
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N. Zekri M. Schreiber R. Ouasti R. Bouamrane A. Brezini 《Zeitschrift für Physik B Condensed Matter》1995,99(3):381-386
A Kronig-Penney model with a constant electric field is used to study the transmission properties of a non-interacting electron one-dimensional (1D) ordered and disordered systems with uniformly distributed negative strengths of δ-function potentials (wells). In ordered systems we examine the origin of the jumps of the transmission coefficient and the short-range localization (occurring before the first jump) observed previously. For disordered wells, we also examine the phase-diagram in the energy-disorder plane. The short-range localization is observed as a peak in the inverse participation ratio and as a minimum in the localization length. We found that the two distinctive behaviours correspond to a negative differential resistance and to a resonance at particular points corresponding to the edges of the Brillouin zones. Further discussions of these behaviours are included. 相似文献
14.
We demonstrate by use of a simple one-dimensional model of a square barrier imbedded in an infinite potential well that decoherence
is enhanced by chaotic-like behavior. We, moreover, show that the transition h→0 is singular. Finally it is argued that the
time scale on which decoherence occurs depends, on the degree of complexity of the underlying quantum mechanical system, i.e.,
more complex systems decohere relatively faster than less complex ones. 相似文献
15.
We revisit the quantum decoherence problem of the center of mass motion of a macroscopic object,which is modelled as a one-dimensional atom chain.Induced by the coupling of the center of mass (C.M) motion with the inner degrees of freedom,this inner-environment-induced decoherence is reflected by the localization of the C.M wave packet.We show that,the C.M motion is coupled to the inner states only when the chain has interaction with the external potential.This result provides a realistic mechanism for the analysis of the inner-environment-induced localization of a macroscopic object. 相似文献
16.
D.M. Basko 《Annals of Physics》2011,(7):1577-1655
The subject of this study is the long-time equilibration dynamics of a strongly disordered one-dimensional chain of coupled weakly anharmonic classical oscillators. It is shown that chaos in this system has a very particular spatial structure: it can be viewed as a dilute gas of chaotic spots. Each chaotic spot corresponds to a stochastic pump which drives the Arnold diffusion of the oscillators surrounding it, thus leading to their relaxation and thermalization. The most important mechanism of equilibration at long distances is provided by random migration of the chaotic spots along the chain, which bears analogy with variable-range hopping of electrons in strongly disordered solids. The corresponding macroscopic transport equations are obtained. 相似文献
17.
N. Zekri M. Schreiber R. Ouasti R. Bouamrane A. Brezini 《Zeitschrift für Physik B Condensed Matter》1995,99(1):381-386
A Kronig-Penney model with a constant electric field is used to study the transmission properties of a non-interacting electron
one-dimensional (1D) ordered and disordered systems with uniformly distributed negative strengths of δ-function potentials
(wells). In ordered systems we examine the origin of the jumps of the transmission coefficient and the short-range localization
(occurring before the first jump) observed previously. For disordered wells, we also examine the phase-diagram in the energy-disorder
plane. The short-range localization is observed as a peak in the inverse participation ratio and as a minimum in the localization
length. We found that the two distinctive behaviours correspond to a negative differential resistance and to a resonance at
particular points corresponding to the edges of the Brillouin zones. Further discussions of these behaviours are included. 相似文献
18.
Based on a tight-binding disordered model describing a single electron band,
we establish a direct current (dc) electronic hopping transport conductance
model of one-dimensional diagonal disordered systems, and also derive a dc
conductance formula. By calculating the dc conductivity, the relationships
between electric field and conductivity and between temperature and
conductivity are analysed, and the role played by the degree
of disorder in electronic
transport is studied. The results indicate the conductivity of systems
decreasing with the increase of the degree of disorder, characteristics of
negative differential dependence of resistance on temperature at low
temperatures in diagonal disordered systems, and the conductivity of systems
decreasing with the increase of electric field, featuring the non-Ohm's law
conductivity. 相似文献
19.
《Physics letters. A》2014,378(16-17):1043-1048
An expectation-based approach to the statistical theorem is proposed for the one-dimensional randomly disordered phononic crystal. In the proposed approach, the expectations of the random eigenstates of randomly disordered phononic crystals are investigated. In terms of the expectations of the random eigenstates, the wave propagation and localization phenomenon in the random phononic crystal could be understood in a statistical perspective. Using the proposed approach, it is proved that for a randomly disordered phononic crystal, the Bloch theorem holds in the perspective of expectation. A one-dimensional randomly disordered binary phononic crystal consisting of two materials with the random geometry size or random physical parameter is addressed by using the proposed approach. From the result, it can be observed that with the increase of the disorder degree, the localization of the expectations of the eigenstates is strengthened. The effect of the random disorder on the eigenstates at higher frequencies is more significant than that at lower frequencies. Furthermore, after introducing the random disorder into phononic crystals, some random divergent eigenstates are changed to localized eigenstates in expectation sense. 相似文献
20.
在单电子紧束缚无序模型基础上,建立了一维二元关联无序体系电子跳跃输运直流电导模型,并推导了其直流电导公式,通过计算其直流电导率,探讨了格点能量无序度、非对角关联及温度、外场对体系跳跃电导的影响.计算结果表明,一维二元无序体系的直流电导率随着格点能量无序度的增大而减小;当引入非对角关联时,体系出现退局域化现象,从而使体系的直流电导率增大;温度对体系的电子输运的影响表现为体系的直流电导率随温度的升高而增大;在外加电场的调制下,体系的直流电导率在强场区随电场强度增加而增长很快,呈现出非欧姆定律特性,但在弱场区外场的作用不明显.
关键词:
二元无序体系
跳跃电导
格点能量无序度
非对角关联 相似文献