The effective action for QED in curved spacetime includes equivalence principle violating interactions between the electromagnetic field and the spacetime curvature. These interactions admit the possibility of superluminal yet causal photon propagation in gravitational fields. In this paper, we extend our analysis of photon propagation in gravitational backgrounds to the Kerr spacetime describi...

Creation of correlated photon pairs is one the key topics in contemporary quantum optics. Here, we theoretically describe generation process spontaneous parametric down-conversion a resonant spherical nanoparticle made dielectric material with bulk $\chi^{(2)}$ nonlinearity. We pick size that satisfies condition eigenmodes described by Mie theory. reveal highly directional photon-pair can be ob...

Context. The interpretation of polarised radiation emerging from a planetary atmosphere must rely on solutions to the vector radiative transport equation (VRTE). Monte Carlo integration of the VRTE is a valuable approach for its flexible treatment of complex viewing and/or illumination geometries, and it can intuitively incorporate elaborate physics. Aims. We present a novel pre-conditioned bac...

Abstract Photonic qubits play an instrumental role in the development of advanced quantum technologies, including networking, boson sampling and measurement based computing. A promising framework for deterministic production indistinguishable single photons is atomic emitter coupled to a mode high finesse optical cavity. Polarisation control important cornerstone, particularly when polarisation...

COMPASS measurements of the gluon polarisation in nucleon, ∆G/G, are reviewed. Two different approaches based on tagging the Photon Gluon Fusion process are described. They rely on the open charm meson or high–pT hadron pairs detection. The obtained results are: −0.57 ± 0.41 (stat.) ± 0.17 (syst.) for the open charm, 0.06 ± 0.31 (stat.) ± 0.06 (syst.) and 0.016 ± 0.058 (stat.) ± 0.055 (syst.) f...

Exclusive electroproduction of π + mesons was studied by scattering 27.6 GeV positrons or electrons off a gaseous hydrogen target. The spin-averaged cross section and the single-spin azimuthal asymmetry with respect to transverse target polarisation were measured as a function of the Man-delstam variable t, the Bjorken scaling variable x B , and the virtuality Q 2 of the exchanged photon. The r...

We discuss the possibility of generating and detecting, by a tomographic reconstruction of the Wigner function, a macroscopic superposition of two coherent states. The superposition state is created using a conditioned measurement on the polarisation of a probe photon entangled to a coherent state. The entanglement is obtained using a Kerr cell inserted in a Mach-Zender interferometer. Some hin...

The nature of superluminal photon propagation in the gravitational field describing radiation from a time-dependent, isolated source (the Bondi-Sachs metric) is considered in an effective theory which includes interactions which violate the strong equivalence principle. Such interactions are, for example, generated by vacuum polarisation in conventional QED in curved spacetime. The relation of ...

Abstract. From the analysis of measurements of the linear polarisation of visible light coming from quasars, the existence of large-scale coherent orientations of quasar polarisation vectors in some regions of the sky has been reported. Here, we show that this can be explained by the mixing of the incoming photons with nearly massless pseudoscalar (axion-like) particles in extragalactic magneti...