Quantum cryptography is a method for providing two parties who want to communicate securely with a secret key to be used in established protocols of classical cryptography. For more reviews of this topic see [1, 2, 3]. Bennett and Brassard showed that it is possible, at least ideally, to create a secret key, shared by sender and receiver, without both parties sharing any secret beforehand. We r...

There is quite a number of puzzling phenomena in astrophysics that could be clarified with the existence of very light scalar or pseudoscalar particles, commonly refered to as axion-like particles (a.k.a. ALPs). One of the main reasons is that these hypothetical particles can have a coupling to photons inside external magnetic fields, as in the axion case [1], and can lead to observable signatu...

Atomic bremsstrahlung-polarisation correlation between incoming electrons and outgoing photons may allow to design a polarimeter capable of measuring all components of beam polarisation simultaneously. This device can be called a vector polarimeter. It might allow to test theoretical predictions of correlation coefficients between 1 and 3.5 MeV as well as work as a beam diagnostics device. As a...

Linear polarisation in gamma-ray burst prompt emission is an important diagnostic with the potential to significantly constrain models. The spectrometer aboard INTEGRAL, SPI, has the capability to detect the signature of polarised emission from a bright γ–ray source. GRB 041219a is the most intense burst localised by INTEGRAL with a fluence of 5.7 ×10−4 ergs cm−2 over the energy range 20 keV–8 ...

One of the missing keys in the present understanding of the spin structure of the nucleon is the contribution from the gluons: the so-called gluon polarisation. This quantity can be determined in DIS through the Photon-Gluon Fusion (PGF) process, in which two analysis methods may be used: (i) identifying open charm events or (ii) selecting events with high-p T hadrons. The data used in the pres...

A distributed feedback laser is fabricated in Er3+-doped photonic crystal fibre. Preferential single-mode lasing is obtained with no special consideration of polarisation issues. The results demonstrate practical implementation of a multi-photon writing process for complex structures in these optical fibres. No hydrogen loading and no germanium are involved.

Circular type’ interferometric system for quantum key distribution is proposed. The system has naturally self-alignment and compensation of birefringence and also has enough efficiency against polarisation dependence. Moreover it is easily applicable to multi-party. Key creation with 0.1 photon per pulse at a rate of 1.2KHz with a 5.4% QBER over a 200m fiber was realized. Quantum key distributi...

Purpose of this paper is to suggest a scheme, which can be realised with today’s technology and could be used for entangling a probe to a photon qubit based on polarisation. Using this probe a translucent or a coherent eavesdropping can be performed.

We present results showing that, thanks to axion-photon mixing in external magnetic fields, it is actually possible to produce an effect similar to the one needed to explain the large-scale coherent orientations of quasar polarisation vectors in visible light that have been observed in some regions of the sky.

We propose a quantum transmission based on bi-photons which are doubly-entangled both in polarisation and phase. This scheme finds a natural application in quantum cryptography, where we show that an eventual eavesdropper is bound to introduce a larger error on the quantum communication than for a single entangled bi-photon communication, when he steels the same information.