Related papers: Majorana states for subluminal structured photons
That the speed of light in free space is constant is a cornerstone of modern physics. However, light beams have finite transverse size, which leads to a modification of their wavevectors resulting in a change to their phase and group…
We report a consequence of the orbital angular momentum (OAM) of a beam to its group velocity. We calculate the group velocity $v_g$ of Laguerre-Gauss beam ($\emph{LG}$) with $\ell$ and at $p=0$. The $v_g$ reduction of $\emph{LG}$ beam even…
D. Giovannini et al. (Reports, 20 February 2015, p. 857) reported that they measured spatially structured photons travelling in free space slowing down even in vacuum. Here we present a simple quantum mechanical consideration which shows…
Recent measurements have highlighted that spatially shaped photons travel slower than c, the speed of monochromatic, plane waves in vacuum. Here we investigate the intrinsic delay introduced by `twisting' a photon, i.e. by introducing…
Contemporary observational and theoretical studies on the temporal nature of microscopic measurements renewed the discussion about the fundamental constants, leading to the possibility of light speed variation and superluminal pulse…
We unify all existing results on the change of the speed of low--energy photons due to modifications of the vacuum, finding that it is given by a universal constant times the quotient of the difference of energy densities between the usual…
We admit that the vacuum is not empty but is filled with continuously appearing and disappearing virtual fermion pairs. We show that if we simply model the propagation of the photon in vacuum as a series of transient captures within the…
A plane monochromatic wave propagates in vacuum at the velocity of c. However, wave packets limited in space and time are used to transmit energy and information. Here it has been shown based on the wave approach that the on-axis part of…
Today, it is well known that light possesses a linear momentum which is along the propagation direction. Besides, scientists also discovered that light can possess an angular momentum (AM), a spin angular momentum (SAM) associated with…
We extend the relationship between mass and spin angular momentum, described by the bosonic spectrum of positive definite mass particles of the Majorana solution to the Dirac equation, to photons that acquire an effective Proca mass through…
We show that the vacuum permeability and permittivity may originate from the magnetization and the polarization of continuously appearing and disappearing fermion pairs. We then show that if we simply model the propagation of the photon in…
The speed of light ($c$) in a vacuum is independent on a choice of frames to describe the propagation, according to the theory of relativity. We consider how light is characterised in a material, where the speed of light is different from…
We propose a quantum model for the vacuum filled of virtual particle pairs. The main originality of this model is to define a density and a life-time of the virtual particles. Compared to the usual QED $(p,E)$ framework, we add here the…
Photons are excellent information carriers but normally pass through each other without consequence. Engineered interactions between photons would enable applications from quantum information processing to simulation of condensed matter…
QED vacua under the influence of external conditions (background fields, finite temperature, boundary conditions) can be considered as dispersive media whose complex behaviour can no longer be described in terms of a single universal vacuum…
Light beams with an azimuthal phase dependency of $e^{i\ell\phi}$ have helical phase fronts and thus carry orbital angular momentum (OAM), a strictly conserved quantity with propagation. Here, we engineer quasi three-dimensional (3D)…
Vortex $\gamma$ photons carrying orbital angular momenta (OAM) hold great potential for various applications. However, their generation remains a great challenge. Here, we successfully generate sub-MeV vortex $\gamma$ photons via…
The propagation of $\gamma$ rays over very large distances provides new insights on the intergalactic medium and on fundamental physics. On their path to the Earth, $\gamma$ rays can annihilate with diffuse infrared or optical photons of…
The problem of light waves interaction with charged particles becomes more and more complex starting with the case of plane waves, where the analytical solution is well known, to more natural, though more complicated situations which…
The influence of radiative corrections on the photon propagation in a gravitational background is investigated without the low-frequency approximation $\omega \ll m$. The conclusion is made in this way that the velocity of light can exceed…