Photon statistics generation

II. Quantum, Classical, and Semiclassical Analyses of Photon Statistics in Harmonic Generation... 

II. QUANTUM, CLASSICAL, AND SEMICLASSICAL ANALYSES OF PHOTON STATISTICS IN HARMONIC GENERATION ( J. BAJER and A. MIRANOWICZ)... 

One way of studying temporal coherence in laser systems is by measuring photon statistics [224]. In this technique the transient laser emission properties are measured using pulsed excitation and a time-resolved setup [225], The transient emission curve generated by each pulse above the laser threshold intensity is divided into time intervals that are smaller than the emission coherence time. The number of photons is then measured in each time interval and for each pulse, and a photon number histogram is calculated to obtain the probability distribution function (PDF) of the photons for each time interval. Photon statistics is achieved separately for each time interval, and correlation between different time intervals or between different wavelengths of the emission spectrum can be also studied. It is expected that for coherent radiation the Poisson distribution determines the PDF, whereas for noncoherent light... 

The generation of photons obeys Poisson statistics where the variance is N and the deviation or noise is. The noise spectral density, N/, is obtained by a Fourier transform of the deviation yielding the following at sampling frequency,... 

Consider a one-step process in which particles are generated and recombine with probabilities g(n) and r(n) per unit time. Each generation or recombination is an event in time and we want to know the statistics of these events. An example is a photoconductor in which the recombination takes place under emission of a photon, which can be registered. We shall concentrate on the recombination events, but the generation events can be treated in the same way. To describe the statistics of these events we employ the functions / introduced in II.3. 

We now turn to a quantitative examination of the feasibility of conditional Fock state generation using our preparation and retrieval technique. For applications in long-distance quantum communication, the quality of the atomic state preparation is the most important quantity. Assuming perfect atom-photon correlations in the write Raman processes, we can find the density matrix p for the number of atomic spin-wave excitations conditioned on the detection of ns Stokes photons. Here we consider only the spin-wave modes correlated with our detection mode. For example, in the absence of losses and background, the conditional atomic density matrix is simply p(ns) = ns)(ns. Loss on the Stokes channel (characterized by transmission coefficient a.s) leads to a statistical mixture of spin-wave excitations,... 

Some of these carriers may recombine within the emissive layer yielding excited electron-hole pairs, termed excitons. These excitons may be produced in either the singlet or triplet states and may radiatively decay to the ground state by phosphorescence (PL) or fluorescence (FL) pathways (Fig. 1-2). An important figure of merit for electroluminescent materials is the number of photons emitted per electron injected and this is termed the internal quantum efficiency. It is clear, therefore, that the statistical maximum internal efficiency for an EL device is 25% as only one quarter of the excitons are produced in the singlet state. In practice, this maximum value is diminished further because not all of the light generated is visi-... 

In this section, we will generalize our results of Section II. B to describe the processes of the Nth-harmonic generation. Again, we will focus on predictions of the sub-Poissonian photon-number statistics. 

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