scholarly journals Magnetic translation algebra with or without magnetic field in the continuum or on arbitrary Bravais lattices in any dimension

2012 ◽  
Vol 86 (19) ◽  
Author(s):  
Claudio Chamon ◽  
Christopher Mudry
Keyword(s):  
Magnetic Field ◽  
Magnetic Translation ◽  
The Continuum

scholarly journals Active angular tuning and switching of Brewster quasi bound states in the continuum in magneto-optic metasurfaces

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Diego R. Abujetas ◽  
Nuno de Sousa ◽  
Antonio García-Martín ◽  
José M. Llorens ◽  
José A. Sánchez-Gil
Keyword(s):  
Magnetic Field ◽  
Magnetic Dipole ◽  
Bound States ◽  
Electromagnetic Spectrum ◽  
Resonant Modes ◽  
Out Of Plane ◽  
Q Factors ◽  
The Impact ◽  
The Continuum ◽  
Magneto Optic

Abstract Bound states in the continuum (BICs) emerge throughout physics as leaky/resonant modes that remain, however, highly localized. They have attracted much attention in photonics, and especially in metasurfaces. One of their most outstanding features is their divergent Q-factors, indeed arbitrarily large upon approaching the BIC condition (quasi-BICs). Here, we investigate how to tune quasi-BICs in magneto-optic (MO) all-dielectric metasurfaces. The impact of the applied magnetic field in the BIC parameter space is revealed for a metasurface consisting of lossless semiconductor spheres with MO response. Through our coupled electric/magnetic dipole formulation, the MO activity is found to manifest itself through the interference of the out-of-plane electric/magnetic dipole resonances with the (MO-induced) in-plane magnetic/electric dipole, leading to a rich, magnetically tuned quasi-BIC phenomenology, resembling the behavior of Brewster quasi-BICs for tilted vertical-dipole resonant metasurfaces. Such resemblance underlies our proposed design for a fast MO switch of a Brewster quasi-BIC by simply reversing the driving magnetic field. This MO-active BIC behavior is further confirmed in the optical regime for a realistic Bi:YIG nanodisk metasurface through numerical calculations. Our results present various mechanisms to magneto-optically manipulate BICs and quasi-BICs, which could be exploited throughout the electromagnetic spectrum with applications in lasing, filtering, and sensing.

scholarly journals The continuum intensity as a function of magnetic field

2011 ◽  
Vol 531 ◽  
pp. A112 ◽  
Author(s):  
P. Kobel ◽  
S. K. Solanki ◽  
J. M. Borrero
Keyword(s):  
Magnetic Field ◽  
Continuum Intensity ◽  
The Continuum

scholarly journals DISSIPATIVE 2D ELECTRON ON A TORUS IN EXTERNAL MAGNETIC FIELD: TRANSPORT PROPERTIES AND MAGNETIC TRANSLATIONS

1995 ◽  
Vol 09 (24) ◽  
pp. 3229-3240 ◽  
Author(s):  
G. CRISTOFANO ◽  
D. GIULIANO ◽  
G. MAIELLA ◽  
L. VALENTE
Keyword(s):  
Magnetic Field ◽  
Wave Function ◽  
Transport Properties ◽  
Ground State ◽  
Large Time ◽  
Transverse Magnetic ◽  
The Novel ◽  
Translation Operators ◽  
Magnetic Translation ◽  
Electron Ground State

The effect of dissipation on the electron ground state wave function on a torus in the presence of an external transverse magnetic field is analyzed on large time scales [Formula: see text]. Its extension to the multiparticle center of the mass wave function is also given. The novel transport properties of the system are then studied by applying Laughlin gauge argument with the use of the magnetic translation operators.

scholarly journals Properties of the Solar Filigree Structure

1974 ◽  
Vol 56 ◽  
pp. 45-47
Author(s):  
R. B. Dunn ◽  
J. B. Zirker ◽  
J. M. Beckers
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
Solar Physics ◽  
List Type ◽  
Blue Wing ◽  
One To One ◽  
Granulation Pattern ◽  
Network Patterns ◽  
The Magnetic Field ◽  
The Continuum

A number of observers have noted the presence of bright structures near the cores of the chromospheric rosettes when observed in the far wings of the Hα line (eg Hα ±7/8 Å). Dunn and Zirker observed these bright structures with the highest possible resolution using the Sacramento Peak vacuum solar telescope. They find that these bright regions exhibit a very intricate fine structure which can be followed out much further into the Hα line wing (eg Hα + 2 Å) and even into the continuum. They called this fine structure ‘solar filigree’, the name referring mainly to the collective appearance of the fine structure elements. The elements themselves appear as dot-like structures and frequently also as small wiggly structures called ‘crinkles’. The properties of the filigree structure are summarized as follows: (i)Size: Measured diameter of the crinkles and dots equals 0.25, 0.40 and 0.60″ at Hα + 2 Å, Hα ± 7/8 Å and Hα ±5/8 Å respectively. The telescope resolution equals 0.22″ so that at Hα + 2 Å the structure is extremely small. The drawings in Figure 1 show typical sizes of the crinkles and network patterns in the filigree.(ii)Contrast: Filigree is enhanced in the blue wing of the Hα line. Measured contrast, uncorrected for seeing, equals 5–10%.(iii)Relation to the Granulation: The filigree structures tend to lie between the granules. This is, however, not a strict rule. It seems that in the course of their lifetime the granules move the filigree structures around with velocities of about 1.5 km s-1. Some of the crinkles also seem to wash out temporarily until compressed again by a new granule. The detailed structure of the filigree, therefore, changes significantly over times comparable to the granule lifetime. The overall structure is, however, preserved over much longer periods of time. The granulation pattern when observed in the continuum well outside the Hα line appears very peculiar in that it has substantially decreased in contrast. It appears ‘soft’ similar to granulation washed-out by seeing. This abnormal granulation can be traced over long times (> 30 min) and coincides in location to the filigree location. It is, therefore, definitely real.(iv)Relation to the spicules: The filigree structure falls near the center of the Hα chromospheric rosettes. These rosettes consist of dark elongated mottles which should probably be identified with spicules. There is, therefore, at least a coarse relation between the occurrence of spicules and the filigree. There is no clear evidence that variations in the filigree pattern are related to the generation of spicules. Some spicules seem to originate from the spaces between the crinkles. Too few, however, to conclude a definite relation.(v)Relation to the magnetic field: Beckers studied the filigree with the Universal Birefringent Filter in the magnesium b1 and b2 lines. It is very well visible in the far wing of the lines (eg. b1 ±0.8 Å). When traced into the line core the structures increase somewhat in size, as they do in Hα, and form structures similar to, and perhaps identical with, the so-called photospheric network. In the magnetically sensitive b2 line one sees a one-to-one correspondence between these network structures and the magnetic field so that, at least in the layers seen near the core of the b2 line, there is a one-to-one correspondence between the filigree structures and the enhancements in the magnetic field. Simon and Zirker (Solar Physics, submitted for publication) using a spectrograph also found that the filigree occurs in regions of enhanced magnetic field. However, in contrast to the filter observations, they found the magnetic field regions to be much more diffuse (2–3″) so that there is not a one-to-one spatial correspondence between filigree and magnetic field structure.

scholarly journals No universal connection between the vertical magnetic field and the umbra-penumbra boundary in sunspots

2020 ◽  
Vol 639 ◽  
pp. A106
Author(s):  
B. Löptien ◽  
A. Lagg ◽  
M. van Noort ◽  
S. K. Solanki
Keyword(s):  
Magnetic Field ◽  
Statistical Analysis ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Filling Factor ◽  
Spot Size ◽  
Vertical Magnetic Field ◽  
Continuum Intensity ◽  
The Mean ◽  
The Continuum

Context. It has been reported that the boundary between the umbra and the penumbra of sunspots occurs at a canonical value of the strength of the vertical magnetic field, independently of the size of the spot. This critical field strength is interpreted to be the threshold for the onset of magnetoconvection. Aims. Here we investigate the reasons why this criterion, also called the Jurčák criterion in the literature, does not always identify the boundary between the umbra and the penumbra. Methods. We performed a statistical analysis of 23 sunspots observed with Hinode/SOT. We compared the properties of the continuum intensity and the vertical magnetic field between filaments and spines and how they vary between spots of different sizes. Results. We find that the inner boundary of the penumbra is not related to a universal value of the vertical magnetic field. The properties of spines and filaments vary between spots of different sizes. Both components are darker in larger spots and the spines exhibit a stronger vertical magnetic field. These variations of the properties of filaments and spines with the spot size are also the reason for the reported invariance in the averaged vertical magnetic field at 50% of the mean continuum intensity. Conclusions. The formation of filaments and the onset of magnetoconvection are not related to a canonical value of the strength of the vertical magnetic field. The seemingly unique magnetic field strength is rather an effect of the filling factor of spines and penumbral filaments.

The Continuum Energy Distribution of the Old-Nova GK Per (1901)

1983 ◽  
Vol 72 ◽  
pp. 127-131
Author(s):  
A. Bianchini ◽  
F. Sabbadin
Keyword(s):  
Magnetic Field ◽  
Energy Distribution ◽  
White Dwarf ◽  
Late Type ◽  
X Ray ◽  
Physical Mechanisms ◽  
Continuum Energy ◽  
Field Lines ◽  
The Continuum ◽  
Standard Disc

ABSTRACTThe observed X-ray to IR continuum energy distribution of the old-nova GK Per, corrected for the contribution of the late-type secondary and for i.s. extinction,is found to be consistent with the model of an accreting magnetic white dwarf. Furthermore, we discuss plausible modifications of the standard disc structure caused by the presence of magnetic field lines threading the disc and evaluate the contribution to the observed radiation field from several physical mechanisms.

scholarly journals Lattice Effects in the Complex Subband Dispersion of 2DEG Semiconductor Waveguide Structures Subjected to a Perpendicular Magnetic Field

VLSI Design ◽  
1998 ◽  
Vol 6 (1-4) ◽  
pp. 31-34
Author(s):  
G. Edwards ◽  
D. K. Ferry
Keyword(s):  
Magnetic Field ◽  
Lattice Model ◽  
Numerical Solutions ◽  
Electron Gas ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Real Solutions ◽  
Lattice Effects ◽  
Dimensional Electron Gas ◽  
The Continuum

In modeling waveguide magneto-transport experiments (in a quasi-two dimensional electron gas), it is important to have knowledge of the electronic states in a magnetic field perpendicular to the plane of the waveguide confinement potential. We present numerical results, within a lattice model, for the full complex subband dispersion of a rectangular waveguide. The form of our numerical real-subband solutions agrees well with analytical real solutions. However, some of our numerical evanescent solutions have a different topology from the analytic evanescent solutions near the bandedges. We argue that our evanescent solutions, although consistent with the symmetry of the lattice model and mode conservation in the restricted Hilbert space of the discretized Hamiltonian, yield different results that are forbidden in the continuum solutions. This is a concern for numerical solutions.

scholarly journals Kondo-excitons and Auger processes in self-assembled quantum dots

2002 ◽  
Vol 737 ◽  
Author(s):  
A. O. Govorov ◽  
K. Karrai ◽  
R. J. Warburton ◽  
A. V. Kalameitsev
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Electron Spin ◽  
Electron Gas ◽  
Kondo Temperature ◽  
Two Dimensional ◽  
Wetting Layer ◽  
Voltage Dependent ◽  
Self Assembled ◽  
The Continuum

ABSTRACTWe describe theoretically novel excitons in self-assembled quantum dots interacting with a two-dimensional (2D) electron gas in the wetting layer. In the presence of the Fermi sea, the optical lines become strongly voltage-dependent. If the electron spin is nonzero, the width of optical lines is given by kBTK, where TK is Kondo temperature. If the spin is zero, the exciton couples with the continuum due to Auger-like processes. This leads to anticrossings in a magnetic field. Such states can be called Kondo-Anderson excitons. Some of the described phenomena are observed in recent experiments.

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