scholarly journals Relativistic Landau quantization in non-uniform magnetic field and its applications to white dwarfs and quantum information

2021 ◽  
Vol 11 (5) ◽  
Author(s):  
Srishty Aggarwal ◽  
Banibrata Mukhopadhyay ◽  
Gianluca Gregori
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Quantum Information ◽  
Magnetic Fields ◽  
White Dwarfs ◽  
Energy Levels ◽  
Landau Levels ◽  
Constant Field ◽  
Angular Momenta ◽  
Spatially Varying

We investigate the two-dimensional motion of relativistic cold electrons in the presence of `strictly’ spatially varying magnetic fields satisfying, however, no magnetic monopole condition. We find that the degeneracy of Landau levels, which arises in the case of the constant magnetic field, lifts out when the field is variable and the energy levels of spin-up and spin-down electrons align in an interesting way depending on the nature of change of field. Also, the varying magnetic field splits Landau levels of electrons with zero angular momentum from positive angular momentum, unlike the constant field which only can split the levels between positive and negative angular momenta. Exploring Landau quantization in non-uniform magnetic fields is a unique venture on its own and has interdisciplinary implications in the fields ranging from condensed matter to astrophysics to quantum information. As examples, we show magnetized white dwarfs, with varying magnetic fields, involved simultaneously with Lorentz force and Landau quantization affecting the underlying degenerate electron gas, exhibiting a significant violation of the Chandrasekhar mass-limit; and an increase in quantum speed of electrons in the presence of a spatially growing magnetic field.

scholarly journals Masses and Magnetic Fields of White Dwarfs in Cataclysmic Variables

1989 ◽  
Vol 114 ◽  
pp. 337-340
Author(s):  
J.P. Lasota ◽  
J.M. Hameury ◽  
A.R. King
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Strong Support ◽  
Drastic Reduction ◽  
Secondary Star ◽  
Maximum Magnetic Field

We show that the existence of the AM Her period spike implies (i) a unique white dwarf mass ≃ 0.6 − 0.7M⊙ for most magnetic CV’s (ii) nova explosions remove exactly the accreted mass from magnetic white dwarfs, and (iii) the maximum magnetic field for most CV’s is ≤ 4 × 107 G. The existence of the spike is very strong support for the idea that the period gap results from a drastic reduction of angular momentum losses when the secondary star becomes fully convective.

scholarly journals Spin-1/2 Particles under the Influence of a Uniform Magnetic Field in the Interior Schwarzschild Solution

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 467
Author(s):  
Fayçal Hammad ◽  
Alexandre Landry ◽  
Parvaneh Sadeghi
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Total Mass ◽  
Uniform Magnetic Field ◽  
Energy Levels ◽  
Relativistic Wave Equation ◽  
Relativistic Wave ◽  
Schwarzschild Solution ◽  
Relativistic Regime ◽  
The Magnetic Field

The relativistic wave equation for spin-1/2 particles in the interior Schwarzschild solution in the presence of a uniform magnetic field is obtained. The fully relativistic regime is considered, and the energy levels occupied by the particles are derived as functions of the magnetic field, the radius of the massive sphere and the total mass of the latter. As no assumption is made on the relative strengths of the particles’ interaction with the gravitational and magnetic fields, the relevance of our results to the physics of the interior of neutron stars, where both the gravitational and the magnetic fields are very intense, is discussed.

LANDAU LEVELS AND VERTEX OPERATIONS FOR ANYONS

1991 ◽  
Vol 06 (30) ◽  
pp. 2819-2826 ◽  
Author(s):  
GERALD V. DUNNE ◽  
ALBERTO LERDA ◽  
CARLO A. TRUGENBERGER
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
External Magnetic Field ◽  
String Theory ◽  
Ground State ◽  
Correlation Functions ◽  
Landau Levels ◽  
Vertex Operators ◽  
Many Body

We construct exact many-body eigenstates of both energy and angular momentum for the N-anyon problem in an external magnetic field. We show that such states span the full ground state eigenspace and arise as correlation functions of Fubini-Veneziano vertex operators of string theory.

scholarly journals Magnetic Fields in OH Maser Clouds

1974 ◽  
Vol 60 ◽  
pp. 275-292 ◽  
Author(s):  
R. D. Davies
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Field Data ◽  
Zeeman Splitting ◽  
Galactic Rotation ◽  
Magnetic Field Data ◽  
The Magnetic Field ◽  
Maser Sources

Observations of Class I OH maser sources show a range of features which are predicted on the basis of Zeeman splitting in a source magnetic field. Magnetic field strengths of 2 to 7 mG are derived for eight OH maser sources. The fields in all the clouds are directed in the sense of galactic rotation. A model of W3 OH is proposed which incorporates the magnetic field data. It is shown that no large amount of magnetic flux or angular momentum has been lost since the condensation from the interstellar medium began.

scholarly journals Galactic Dynamics and Magnetic Field Amplification

1993 ◽  
Vol 157 ◽  
pp. 395-401 ◽  
Author(s):  
Harald Lesch
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
Time Scale ◽  
Numerical Models ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Field Amplification ◽  
Gravitational Instabilities ◽  
Magnetic Diffusivity

Stimulated by recent high frequency radio polarization measurements of M83 and M51, we consider the influence of non-axisymmetric features (bars, spiral arms, etc…) on galactic magnetic fields. The time scale for the field amplification due to the non-axisymmetric velocity field is related to the time scale of angular momentum transport in the disk by the non-axisymmetric features. Due to its dissipational character (cooling and angular momentum transport) the gas plays a major role for the excitation of non-axisymmetric instabilities. Since it is the gaseous component of the interstellar gas in which magnetic field amplification takes place we consider the interplay of gasdynamical processes triggered by gravitational instabilities and magnetic fields. A comparison with the time scale for dynamo action in a disk from numerical models for disk dynamos gives the result that field amplification by non-axisymmetric features is faster in galaxies like M83 (strong bar) and M51 (compagnion and very distinct spiral structure), than amplification by an axisymmetric dynamo. Furthermore, we propose that axisymmetric gravitational instabilities may provide the turbulent magnetic diffusivity ηT. Based on standard galaxy models we obtain a radially dependent diffusivity whose numerical value rises from 1025cm2s−1 to 1027cm2s−1, declining for large radii.

scholarly journals Discrete spectrum of many body Schrödinger operators with non-constant magnetic fields II

1997 ◽  
Vol 145 ◽  
pp. 69-98
Author(s):  
Tetsuya Hattori
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Discrete Spectrum ◽  
Bound States ◽  
Atomic System ◽  
Energy Levels ◽  
Schrödinger Operators ◽  
Schrodinger Operators ◽  
Many Body ◽  
Discrete Energy

This paper is continuation from [10], in which we studied the discrete spectrum of atomic Hamiltonians with non-constant magnetic fields and, more precisely, we showed that any atomic system has only finitely many bound states, corresponding to the discrete energy levels, in a suitable magnetic field. In this paper we show another phenomenon in non-constant magnetic fields that any atomic system has infinitely many bound states in a suitable magnetic field.

scholarly journals Discovery of weak magnetic fields in four DZ white dwarfs in the local 20 pc volume

2019 ◽  
Vol 630 ◽  
pp. A65 ◽  
Author(s):  
S. Bagnulo ◽  
J. D. Landstreet
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
White Dwarfs ◽  
Field Measurements ◽  
Weak Magnetic Fields ◽  
Polluted Atmosphere ◽  
Highly Sensitive ◽  
Cool White Dwarfs ◽  
The Magnetic Field ◽  
Made In

We report the discovery of weak magnetic fields in three white dwarfs within the local 20 pc volume (WD 0816−310, WD 1009−184, and WD 1532+129), and we confirm the magnetic nature of a fourth star (WD 2138−332) in which we had previously detected a field at a 3σ level. The spectra of all these white dwarfs are characterised by the presence of metal lines and lack of H and He lines, that is, they belong to the spectral class DZ. The polarisation signal of the Ca II H+K lines of WD 1009−184 is particularly spectacular, with an amplitude of 20% that is due to the presence of a magnetic field with an average line-of-sight component of 40 kG. We have thus established that at least 40% of the known DZ white dwarfs with an He-rich atmosphere contained in the 20 pc volume have a magnetic field, while further observations are needed to establish whether the remaining DZ white dwarfs in the same volume are magnetic or not. Metal lines in the spectra of DZ white dwarfs are thought to have originated by accretion from rocky debris, and it might be argued that a link exists between metal accretion and higher occurrence of magnetism. However, we are not able to distinguish whether the magnetic field and the presence of a polluted atmosphere have a common origin, or if it is the presence of metal lines that allows us to detect a higher frequency of magnetic fields in cool white dwarfs, which would otherwise have featureless spectra. We argue that the new highly sensitive longitudinal field measurements that we have made in recent years are consistent with the idea that the magnetic field appears more frequently in older than in younger white dwarfs.

scholarly journals Clues to the origin and properties of magnetic white dwarfs

2019 ◽  
Vol 15 (S357) ◽  
pp. 60-74
Author(s):  
Adela Kawka
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
White Dwarfs ◽  
Field Structure ◽  
Complex Structures ◽  
Surface Mapping ◽  
Time Resolved ◽  
Single Star ◽  
Rotation Rates ◽  
Star Evolution

AbstractA significant fraction of white dwarfs possess a magnetic field with strengths ranging from a few kG up to about 1000 MG. However, the incidence of magnetism varies when the white dwarf population is broken down into different spectral types providing clues on the formation of magnetic fields in white dwarfs. Several scenarios for the origin of magnetic fields have been proposed from a fossil field origin to dynamo generation at various stages of evolution. Offset dipoles are often assumed sufficient to model the field structure, however time-resolved spectropolarimetric observations have revealed more complex structures such as magnetic spots or multipoles. Surface mapping of these field structures combined with measured rotation rates help distinguish scenarios involving single star evolution from other scenarios involving binary interactions. I describe key observational properties of magnetic white dwarfs such as age, mass, and field strength, and confront proposed formation scenarios with these properties.

Thermal geometric discords in a two-qutrit system

2016 ◽  
Vol 14 (03) ◽  
pp. 1650016 ◽  
Author(s):  
Ya-Li Yuan ◽  
Xi-Wen Hou
Keyword(s):  
Magnetic Field ◽  
Quantum Information ◽  
Magnetic Fields ◽  
Weak Magnetic Field ◽  
Quantum Discord ◽  
Quantum Information Processing ◽  
Thermal State ◽  
Quantum Correlations ◽  
High Dimensional ◽  
Lower Temperature

The investigation of quantum discord has mostly focused on two-qubit systems due to the complicated minimization involved in quantum discord for high-dimensional states. In this work, three geometric discords are studied for the thermal state in a two-qutrit system with various couplings, external magnetic fields, and temperatures as well, where the entanglement measured in terms of the generalized negativity is calculated for reference. It is shown that three geometric discords are more robust against temperature and magnetic field than the entanglement negativity. However, all four quantities exhibit a similar behavior at lower temperature and weak magnetic field. Remarkably, three geometric discords at finite temperature reveal the phenomenon of double sudden changes at different magnetic fields while the negativity does not. Moreover, the hierarchy among three discords is discussed. Those adjustable discords with the varied coupling, temperature, and magnetic field are useful for the understanding of quantum correlations in high-dimensional states and quantum information processing.

Observation of Hexagonally Ordered Flux Quanta in YBa2Cu3O7

1987 ◽  
Vol 99 ◽  
Author(s):  
P. L. Gammel ◽  
D. J. Bishop ◽  
G. J. Dolan ◽  
J. R. Kwo ◽  
C. A. Murray ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Fundamental Property ◽  
Quantized Vortices ◽  
Constant Field ◽  
High Tc ◽  
Flux Lines ◽  
Show Evidence ◽  
Ordinary Type ◽  
Hexagonally Ordered ◽  
Spatially Varying

ABSTRACTThe high resolution Bitter Pattern technique has been used to reveal the structure of the array of flux lines which is present when single crystal samples of the high Tc superconductor YBa2Cu3O7 are placed in a magnetic field. At 4.2K with the magnetic field parallel to the c axis, the patterns formed are strongly reminiscent of the analogous structures in ordinary type II superconductors. The structures typically consist of flux spots with short range hexagonal correlations. We interpret the patterns to consist of singly quantized vortices. Very uniform patterns are observed in thin, flat samples cooled in a constant field. Sampling the spot density yields a vortex density consistent with a flux quantum of hc/2e.Experiments at 77K, the only other temperature studied, showed no spatially varying magnetic structure. Recent mechanical measurements which are sensitive to the bulk modulus and dissipation within the vortex lattice show evidence for a mobility transition near 75K, which would be consistent with this observation. We believe this stems from materials properties rather than some more fundamental property of the new superconductors.

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