Photon-number Distribution Function Research Articles

Evolution of ultrashort laser pulse in large amplitude plasma waves

The propagation and evolution of an ultrashort laser pulse in a large amplitude plasma wave are investigated based on the photon kinetic theory. The photon number distribution function for a laser pulse in the phase space is analytically obtained by solving the photon kinetic equation in the background plasma wave. And then, the behavior of the laser pulse can be described by combining the single photon dynamics and the photon number distribution function. The evolutions of the photon number density in the coordinate and frequency domain space are discussed, and broadening or compressing of the laser pulse is also displayed in this paper. In particular, the frequency shift of the entire laser pulse is analyzed, which reflects a way of energy transformation between the laser pulse and the plasma wave.

Quantum statistical properties of superposition of squeezed and displaced number states

In this article we introduce general class of quantum states, as a single mode vibration of electromagnetic field, sudden squeezed-plus-displaced by a collection of two displacements 180° out of phase. For such class the quantum statistical quantities, such as the second-order correlation function, quasiprobability distribution functions and the photon-number distribution function are examined analytically and numerically. Generation schemes are proposed. Regimes of strongly nonclassical behaviour of such states are demonstrated.

Is the number of photons conserved in an expanding universe?

A Friedman-like scenario is described in which due to the direct coupling of electromagnetic fields to spacetime curvature-the total number of photons comprised in the Universe at a given epoch changes as the Universe expands. The photon number distribution function, according to this scenario, acquires an explicit dependence on a non-vanishing chemical potential term which accounts for the occurrence of tidal effects in the interaction of photons (which, in a gravitational field, should not be treated as idealised, point-like objects) with gravity. The total amount of entropy observed today may be reviewed from a new perspective and ipso facto explained away.