Experimental multi-photon-resolving detector using a single avalanche photodiode

A multichannel detector has been constructed using a single avalanche photodiode and a fiber-loop delay line. Detection probabilities of the channels can be set using a variable-ratio coupler. The performance of the detector is demonstrated on its capability to distinguish multi-photon states (containing two or more photons) from the one-photon state and the vacuum state.Comment: LATEX, 11 pages, 5 PostScript figure

Characterisation of the Physical Chemical Processes Using the Fractal and Harmonic Analysis

Existuje mnoho různých způsobů jak analyzovat disperzní systémy a fyzikálně chemické processy ke kterým v takových systémech dochází. Tato práce byla zaměřena na charakterizaci těchto procesů pomocí metod harmonické fraktální analýzy. Obrazová data sledovaných systémů byly analyzovány pomocí waveletové analýzy. V průběhu práce byly navrženy různé optimalizace samotné analýzy, převážně zaměřené na odstranění manuálních operací během analýzy a tyto optimalizace byly také inkorporovány do softérového vybavení pro Harmonickou Fraktální Analýzu HarFA, který je vyvíjen na Fakultě chemické, VUT Brno.There are many different ways to characterize the dispersed systems and processes occuring in such systems. This work focuses on use of Fractal properties of such systems to describe the physical and chemical processes occuring in such systems. The Fractal properties are calculated from the image data of the systems under the observation using the Wavelet analysis. Since the Harmonic Fractal Analysis can be relatively easily automated, the work also focuses on algorithmisation of the analysis and the removal all manual steps from the process. The automation have been performed by incorporating all the findings into the software for Harmonic Fractal Analysis HarFA developed at the Faculty of Chemistry, BUT.

Photon-number distributions of twin beams generated in spontaneous parametric down-conversion and measured by an intensified CCD camera

The measurement of photon-number statistics of fields composed of photon pairs, generated in spontaneous parametric down-conversion and detected by an intensified CCD camera is described. Final quantum detection efficiencies, electronic noises, finite numbers of detector pixels, transverse intensity spatial profiles of the detected beams as well as losses of single photons from a pair are taken into account in a developed general theory of photon-number detection. The measured data provided by an iCCD camera with single-photon detection sensitivity are analyzed along the developed theory. Joint signal-idler photon-number distributions are recovered using the reconstruction method based on the principle of maximum likelihood. The range of applicability of the method is discussed. The reconstructed joint signal-idler photon-number distribution is compared with that obtained by a method that uses superposition of signal and noise and minimizes photoelectron entropy. Statistics of the reconstructed fields are identified to be multi-mode Gaussian. Elements of the measured as well as the reconstructed joint signal-idler photon-number distributions violate classical inequalities. Sub-shot-noise correlations in the difference of the signal and idler photon numbers as well as partial suppression of odd elements in the distribution of the sum of signal and idler photon numbers are observed.Comment: 14 pages, 14 figure

Absolute calibration of photon-number-resolving detectors with an analog output using twin beams

A method for absolute calibration of a photon-number resolving detector producing analog signals as the output is developed using a twin beam. The method gives both analog-to-digital conversion parameters and quantum detection efficiency for the photon fields. Characteristics of the used twin beam are also obtained. A simplified variant of the method applicable to fields with high signal to noise ratios and suitable for more intense twin beams is suggested.Comment: 4 pages, 3 figure