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We consider wave functions in the Hilbert space $\mathcal{H}=L^2(\mathbb{R}^3,\mathbb{C}^4)$ of a single Dirac particle, specifically from the positive-energy subspace $\mathcal{H}_+$ of the free Dirac Hamiltonian. Over the decades, various…

Quantum Physics · Physics 2026-03-10 Ilmar Bürck , Roderich Tumulka

The group velocity of gravitational waves in a flat Friedman-Robertson-Walker universe is investigated. For plane waves with wavelength well inside the horizon, and a universe filled with an ideal fluid with the pressure to density ratio…

General Relativity and Quantum Cosmology · Physics 2011-02-01 Vladimír Balek , Vratko Polák

Quantum simulation is a powerful tool to study a variety of problems in physics, ranging from high-energy physics to condensed-matter physics. In this article, we review the recent theoretical and experimental progress in quantum simulation…

Quantum Gases · Physics 2012-03-28 Dan-Wei Zhang , Zi-Dan Wang , Shi-Liang Zhu

We study the traversal times of electromagnetic pulses across dispersive media with negative dielectric permittivity ($\varepsilon$) and magnetic permeability ($\mu$) parameters. First we investigate the transport of optical pulses through…

Materials Science · Physics 2008-12-08 Lipsa Nanda , S. Anantha Ramakrishna

The concept of phase and dwell times used in tunneling is extended to quantum collisions to derive a relation between the phase and dwell time delays in scattering. This relation can be used to remove the near threshold s-wave singularities…

Quantum Physics · Physics 2008-11-26 Neelima G. Kelkar

The slowing down of a charged particle beam passing through the dusty plasma with a non-thermal velocity alpha-distribution is studied. By using the Fokker-Planck collision theory, we derive the deceleration factor and slowing down time and…

Plasma Physics · Physics 2023-09-29 Yu Wang , Jiulin Du

It is reported that when a light beam travels through a slab of left-handed medium in the air, the lateral shift of the transmitted beam can be negative as well as positive. The necessary condition for the lateral shift to be positive is…

Optics · Physics 2009-11-10 Xi Chen , Chun-Fang Li

One route towards understanding both fractional charges and chiral anomalies delves into Dirac's negative energy sea. Usually we think of Dirac's negative energy sea as an unphysical construct, invented to render quantum field theory…

High Energy Physics - Theory · Physics 2007-05-23 R. Jackiw

We show, in the framework of a space-time resolved relativistic quantum field theory approach to tunneling, that microcausality precludes superluminal tunneling dynamics. More specifically in this work dealing with Dirac and Klein-Gordon…

Quantum Physics · Physics 2025-11-04 Mohammed Alkhateeb , Alex Matzkin

Quantum tunneling between two potential wells in a magnetic field can be strongly increased when the potential barrier varies in the direction perpendicular to the line connecting the two wells and remains constant along this line. A…

Quantum Physics · Physics 2007-05-23 Boris Ivlev

Using a recently developed procedure - multiple wave packet decomposition - here we study the phase time formulation for tunneling/reflecting particles colliding with a potential barrier. To partially overcome the analytical difficulties…

Quantum Physics · Physics 2009-11-10 Alex E. Bernardini

We obtain an exact solution of the 1D Dirac equation for a square well potential of depth greater then twice the particle's mass. The energy spectrum formula in the Klein zone is surprisingly very simple and independent of the depth of the…

Quantum Physics · Physics 2015-05-13 A. D. Alhaidari

We study the transmission and group delay time for fermions in graphene under a proximity exchange field scattered by double barriers. Solving the Dirac equation over five regions, we calculate transmission and reflection coefficients using…

Mesoscale and Nanoscale Physics · Physics 2025-03-06 Ahmed Jellal , Rachid El Aitouni , Pablo Díaz , David Laroze

The relationship between the Dirac and reduced phase space quantizations is investigated for spin models belonging to the class of Hamiltonian systems having no gauge conditions. It is traced out that the two quantization methods may give…

High Energy Physics - Theory · Physics 2007-05-23 Mikhail S. Plyushchay , Alexander V. Razumov

A filter for universal real-time prediction of band-limited signals is presented. The filter consists of multiple time-delayed feedback terms in order to accomplish anticipatory coupling, which again leads to a negative group delay for…

Sound · Computer Science 2017-11-29 Henning U. Voss

This paper is an investigation of the class of real classical Markov processes without a birth process that will generate the Dirac equation in 1+1 dimensions. The Markov process is assumed to evolve in an extra (ordinal) time dimension.…

Quantum Physics · Physics 2007-05-23 M. Ibison

Some solutions describing vacuum decay exhibit a catastrophic instability. This, so-called negative mode problem in quantum tunneling with gravity, was discovered 34 years ago and in spite of the fact that in these years many different…

General Relativity and Quantum Cosmology · Physics 2019-12-11 Sebastian F. Bramberger , Mariam Chitishvili , George Lavrelashvili

The arrival time probability distribution is defined by analogy with the classical mechanics. The difficulty of requirement to have the values of non-commuting operators is circumvented using the concept of weak measurements. The proposed…

Quantum Physics · Physics 2009-11-10 J. Ruseckas , B. Kaulakys

Motivated by recent studies in human balance control, we study a delayed random walk with an unstable fixed point. It is observed that the random walker moves away from the unstable fixed point more slowly than is observed in the absence of…

Other Condensed Matter · Physics 2009-11-11 Tadaaki Hosaka , Toru Ohira , Christian Luciani , Juan Luis Cabrera , John G. Milton

We show that certain types of quantum walks can be modeled as waves that propagate in a medium with phase and group velocities that are explicitly calculable. Since the group and phase velocities indicate how fast wave packets can propagate…

Quantum Physics · Physics 2013-05-29 Achim Kempf , Renato Portugal