High-visibility multi-photon interference of Hanbury Brown - Twiss type for classical light

Difference-phase (or Hanbury Brown - Twiss type) intensity interference of classical light is considered in higher orders in the intensity. It is shown that, while the visibility of sum-phase (NOON-type) interference for classical sources drops with the order of interference, the visibility of difference-phase interference has opposite behavior. For three-photon and four-photon interference of two coherent sources, the visibility can be as high as 81.8% and 94.4%, respectively. High-visibility three-photon and four-photon interference of space-time and polarization types has been observed in experiment, for both coherent and pseudo-thermal light.Comment: 11 pages, 9 figure

Super-bunched bright squeezed vacuum state

In this paper we experimentally study the statistical properties of a bright squeezed vacuum state containing up to 10^13 photons per mode (10 uJ per pulse), produced via high gain parametric down conversion (PDC). The effects of bunching and superbunching of photons were observed for a single mode PDC radiation by second-order intensity correlation function measurements with analog detectors.Comment: 4 pages, 3 figures, submitted to Optics Letter

Nonlinear interferometer for tailoring the frequency spectrum of bright squeezed vacuum

We propose a method for tailoring the frequency spectrum of bright squeezed vacuum by generating it in a nonlinear interferometer, consisting of two down-converting nonlinear crystals separated by a dispersive medium. Due to a faster dispersive spreading of higher-order Schmidt modes, the spectral width of the radiation at the output is reduced as the length of the dispersive medium is increased. Preliminary results show 30\% spectral narrowing.Comment: 9 pages, 6 figure

Microscale generation of entangled photons without momentum conservation

We report, for the first time, the generation of entangled photon pairs via type-0 spontaneous parametric down conversion in an ultra-thin wafer of lithium niobate in which momentum between the pump photon and daughter photons is not conserved. The characteristics of the emission are investigated using several techniques. We find that non-phase matched SPDC is a promising source of ultra-broadband two photon radiation that exhibits remarkably tight correlation widths in both the spatial and temporal domains.Comment: 9 pages, 8 figure

Conditioned Unitary Transformation on biphotons

A conditioned unitary transformation ($90^o$ polarization rotation) is performed at single-photon level. The transformation is realized by rotating polarization for one of the photons of a polarization-entangled biphoton state (signal photon) by means of a Pockel's cell triggered by the detection of the other (idler) photon after polarization selection. As a result, polarization degree for the signal beam changes from zero to the value given by the idler detector quantum efficiency. This result is relevant to practical realization of various quantum information schemes and can be used for developing a new method of absolute quantum efficiency calibration

Two-photon diffraction and quantum lithography

We report a proof-of-principle experimental demonstration of quantum lithography. Utilizing the entangled nature of a two-photon state, the experimental results have bettered the classical diffraction limit by a factor of two. This is a quantum mechanical two-photon phenomenon but not a violation of the uncertainty principle.Comment: 5 pages, 5 figures Submitted to Physical Review Letter

Polarization state of a biphoton: quantum ternary logic

Polarization state of biphoton light generated via collinear frequency-degenerate spontaneous parametric down-conversion is considered. A biphoton is described by a three-component polarization vector, its arbitrary transformations relating to the SU(3) group. A subset of such transformations, available with retardation plates, is realized experimentally. In particular, two independent orthogonally polarized beams of type-I biphotons are transformed into a beam of type-II biphotons. Polarized biphotons are suggested as ternary analogs of two-state quantum systems (qubits)

On Preparing Entangled Pairs of Polarization Qubits in the Frequency Non-Degenerate Regime

The problems associated with practical implementation of the scheme proposed for preparation of arbitrary states of polarization ququarts based on biphotons are discussed. The influence of frequency dispersion effects are considered, and the necessity of group velocities dispersion compensation in the frequency non-degenerate case even for continuous pumping is demonstrated. A method for this compensation is proposed and implemented experimentally. Physical restrictions on the quality of prepared two-photon states are revealed.Comment: 9 pages, 6 figure

EFFECT OF COMPLEX TREATMENT USING PLATELET AUTOPLASMA ON CLINICAL AND LABORATORY PARAMETERS OF PATIENTS WITH ENDOGENOUS UVEITIS AND MACULAR EDEMA

Purpose: to study the clinical and laboratory efficacy of the platelet autoplasma use in the complex treatment of endogenous uveitis associated with systemic diseases accompanied by macular edema. Material and methods. The study included 46 people (72 eyes) with endogenous uveitis and macular edema. The diagnosis was made on the basis of the ophthalmological examination, including visometry, tonometry, biomicroscopy, ophthalmoscopy, perimetry, B-scan, optical coherence tomography of the macular zone, photoregistration of the anterior, posterior segment of the eye. The examination was carried out on the 1st and 10th day of treatment. The main group consisted of 22 people (36 eyes) who underwent anti-inflammatory therapy and the introduction of platelet plasma in the region of the pterygopalatine fossa. The control group consisted of 24 people (36 eyes) receiving only anti-inflammatory therapy (diprospan 0.5 paraequatorially №1, dexazone 4 mg intravenously №5, intravenous lasix 2.0 ml №5, electrophoresis with prednisolone № 7). All patients underwent the definition of IL-4, IL-6, IL-8, IL-17 in tear fluid before the study and on the 10th day. Results. The significant increase in the concentrations of pro-inflammatory cytokines (IL-17A and IL-8) and IL-4 and IL-6 involved in the development of autoimmune response and chronic inflammation was found in the patients with endogenous uveitis and macular edema. The use in the treatment of endogenous uveitis with macular edema of platelet autoplasma leads to more pronounced improvement of clinico-ophthalmological parameters (improvement in visual acuity, retinal photosensitivity, and retinal thickness reduction) relating to the comparison group. A decrease in the activity of the inflammatory process was noted in the main group after treatment, which is manifested by a significant decrease in the concentrations of IL-17A, IL-8, IL-4, IL-6, relating to the data obtained in the comparison group. The proposed scheme of complex treatment allows reducing the frequency of relapses of the pathological process