scholarly journals Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 443-452
Author(s):  
Tianshu Jiang ◽  
Anan Fang ◽  
Zhao-Qing Zhang ◽  
Che Ting Chan
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Waves ◽  
Anderson Localization ◽  
Random Media ◽  
Normal Incidence ◽  
Disordered Media ◽  
One Dimensional ◽  
Gain Loss ◽  
The Waves ◽  
Localization Behavior

AbstractIt has been shown recently that the backscattering of wave propagation in one-dimensional disordered media can be entirely suppressed for normal incidence by adding sample-specific gain and loss components to the medium. Here, we study the Anderson localization behaviors of electromagnetic waves in such gain-loss balanced random non-Hermitian systems when the waves are obliquely incident on the random media. We also study the case of normal incidence when the sample-specific gain-loss profile is slightly altered so that the Anderson localization occurs. Our results show that the Anderson localization in the non-Hermitian system behaves differently from random Hermitian systems in which the backscattering is suppressed.

Anomalous Anderson localization behavior in gain-loss balanced non-Hermitian systems

2021 ◽  
pp. 455-464
Author(s):  
Tianshu Jiang ◽  
Anan Fang ◽  
Zhao-Qing Zhang ◽  
Che Ting Chan
Keyword(s):  
Anderson Localization ◽  
Gain Loss ◽  
Localization Behavior

Rayleigh surface waves along the boundary between a plasma and a metallic screen

1993 ◽  
Vol 49 (2) ◽  
pp. 227-235 ◽  
Author(s):  
S. T. Ivanov ◽  
K. M. Ivanova ◽  
E. G. Alexov
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Surface Waves ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Magnetoactive Plasma ◽  
Rayleigh Surface Waves ◽  
The Waves

Electromagnetic wave propagation along the interface between a magnetoactive plasma and a metallic screen is investigated analytically and numerically. It is shown that the waves have a Rayleigh character: they are superpositions of two partial waves. It is concluded that electromagnetic waves propagate only at frequencies lower than min (ωp, ωc), where ωpis the plasma frequency and ωcis the cyclotron frequency. The field topology is found, and the physical character of the waves is discussed.

Wave Propagation and Instability in a Circular Semi-Infinite Liquid Jet Harmonically Forced at the Nozzle

1978 ◽  
Vol 45 (3) ◽  
pp. 469-474 ◽  
Author(s):  
D. B. Bogy
Keyword(s):  
Wave Propagation ◽  
Radiation Condition ◽  
Liquid Jet ◽  
Propagation Characteristics ◽  
Frequency Spectra ◽  
One Dimensional ◽  
Wave Numbers ◽  
Complex Wave ◽  
The Stability ◽  
The Waves

The linearized form of the inviscid, one-dimensional Cosserat jet equations derived by Green [6] are used to study wave propagation in a circular jet with surface tension. The frequency spectra are shown for complex wave numbers for a complete range of Weber numbers. The propagation characteristics of the waves are studied in order to determine which branches of the frequency spectra to use in the semi-infinite jet problem with harmonic forcing at the nozzle. Two of the four branches are eliminated by a radiation condition that energy must be outgoing at infinity; the remaining two branches are used to satisfy the nozzle boundary conditions. The variation of the jet radius along its length is shown graphically for various Weber numbers and forcing frequencies. The stability or instability is explained in terms of the behavior of the two propagating phases.

scholarly journals Anomalous Anderson localization behaviors in disordered pseudospin systems

2017 ◽  
Vol 114 (16) ◽  
pp. 4087-4092 ◽  
Author(s):  
A. Fang ◽  
Z. Q. Zhang ◽  
Steven G. Louie ◽  
C. T. Chan
Keyword(s):  
Disordered Systems ◽  
Anderson Localization ◽  
Random Potential ◽  
Incident Angle ◽  
Localization Length ◽  
Normal Incidence ◽  
Wave Localization ◽  
Sharp Transition ◽  
Angle Dependence ◽  
Localization Behavior

We discovered unique Anderson localization behaviors of pseudospin systems in a 1D disordered potential. For a pseudospin-1 system, due to the absence of backscattering under normal incidence and the presence of a conical band structure, the wave localization behaviors are entirely different from those of conventional disordered systems. We show that there exists a critical strength of random potential (Wc), which is equal to the incident energy (E), below which the localization length ξ decreases with the random strength W for a fixed incident angle θ. But the localization length drops abruptly to a minimum at W=Wc and rises immediately afterward. The incident angle dependence of the localization length has different asymptotic behaviors in the two regions of random strength, with ξ∝sin−4θ when W<Wc and ξ∝sin−2θ when W>Wc. The existence of a sharp transition at W=Wc is due to the emergence of evanescent waves in the systems when W>Wc. Such localization behavior is unique to pseudospin-1 systems. For pseudospin-1/2 systems, there is also a minimum localization length as randomness increases, but the transition from decreasing to increasing localization length at the minimum is smooth rather than abrupt. In both decreasing and increasing regions, the θ dependence of the localization length has the same asymptotic behavior ξ∝sin−2θ.

SOME ASPECTS OF ELASTIC WAVE PROPAGATION IN FLUID‐SATURATED POROUS SOLIDS

Geophysics ◽  
1961 ◽  
Vol 26 (2) ◽  
pp. 169-181 ◽  
Author(s):  
J. Geertsma ◽  
D. C. Smit
Keyword(s):  
Wave Propagation ◽  
Low Frequency ◽  
Normal Incidence ◽  
Approximate Solutions ◽  
Porous Solids ◽  
Geophysical Research ◽  
Weak Points ◽  
Biot’S Equations ◽  
Second Wave ◽  
The Waves

Biot’s equations for the propagation of dilatational waves in fluid‐saturated porous solids in the low‐frequency range are analyzed for the purpose of application in geophysical research. The deformation constants of the system are unraveled in terms of compressibilities and porosity, and suitable approximate solutions for wave velocity and attenuation of the waves of both the first and the second kind are obtained. A saturated elastic porous solid is found to behave, as far as the wave of the first kind is concerned, approximately as a standard element. The wave of the second kind rapidly dies out with increasing distance from the source and consequently one might infer that in seismic studies only the wave of the first kind needs consideration. It is shown, however, that its presence has an effect upon the reflection and absorption at any interface between two different fluid‐saturated porous solids. At such an interface a wave of the second kind is again generated. General formulae for the reflection and absorption for normal incidence at the interface are obtained, which include the effect of second‐wave generation. Additional results of the investigation are the following: A rather simple formula for the speed of sound in sedimentary rocks (the wave of the first kind) is obtained, which has to replace the so‐called “time‐average relation” now sometimes used. A comparison between the results obtained here and published results on wave propagation in simpler fluid‐solid systems, such as, for instance, suspensions, showed some weak points in the older theories. Suggestions for possible improvements are given.

scholarly journals Charge density waves in disordered media circumventing the Imry-Ma argument

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Hitesh J. Changlani ◽  
Norm M. Tubman ◽  
Taylor L. Hughes
Keyword(s):  
Charge Density ◽  
Anderson Localization ◽  
Charge Density Waves ◽  
Disordered Media ◽  
Biomolecular Systems ◽  
One Dimensional ◽  
Broken Symmetries ◽  
Electrically Conducting ◽  
Theoretical Predictions ◽  
Ordered State

Abstract Two powerful theoretical predictions, Anderson localization and the Imry-Ma argument, impose significant restrictions on the phases of matter that can exist in the presence of even the smallest amount of disorder in one-dimensional systems. These predictions forbid electrically conducting states and ordered states respectively. It was thus remarkable that a mechanism to circumvent Anderson localization relying on the presence of correlated disorder was found, that is also realized in certain biomolecular systems. In a similar manner, we show that the Imry-Ma argument can be circumvented, resulting in the formation of stable ordered states with discrete broken symmetries in disordered one dimensional systems. We then investigate other mechanisms by which disorder can destroy an ordered state.

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