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Search Results: 1 - 10 of 71055 matches for " Maria Chekhova "
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Tailoring polarization entanglement in anisotropy-compensated SPDC
Giorgio Brida,Marco Genovese,Maria V. Chekhova,Leonid A. Krivitsky
Physics , 2007, DOI: 10.1103/PhysRevA.77.015805
Abstract: We show that the angular spectrum of type-II SPDC contains a continuum of maximally entangled states. For the realization of a bright source of entangled two-photon states, a standard technique is to compensate for the transverse walk-off in the production crystal. We demonstrate that polarization entangled states can be effectively engineered by generalizing this approach. Our method allows to considerably enrich the set of generated entangled states with a controlled tailoring them.
Analysis of the possibility of analog detectors calibration by exploiting Stimulated Parametric Down Conversion
Giorgio Brida,Maria Chekhova,Marco Genovese,Ivano Ruo-Berchera
Physics , 2008, DOI: 10.1364/OE.16.012550
Abstract: Spontaneous parametric down conversion (SPDC) has been largely exploited as a tool for absolute calibration of photon-counting detectors, i.e detectors registering very small photon fluxes. In [J. Opt. Soc. Am. B 23, 2185 (2006)] we derived a method for absolute calibration of analog detectors using SPDC emission at higher photon fluxes, where the beam is seen as a continuum by the detector. Nevertheless intrinsic limitations appear when high-gain regime of SPDC is required to reach even larger photon fluxes. Here we show that stimulated parametric down conversion allow one to avoid this limitation, since stimulated photon fluxes are increased by the presence of the seed beam.
Two-photon diffraction and quantum lithography
Milena D'Angelo,Maria V. Chekhova,Yanhua H. Shih
Physics , 2001, DOI: 10.1103/PhysRevLett.87.013602
Abstract: 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.
Two-Color Bright Squeezed Vacuum
Ivan N. Agafonov,Maria V. Chekhova,Gerd Leuchs
Physics , 2009, DOI: 10.1103/PhysRevA.82.011801
Abstract: In a strongly pumped non-degenerate traveling-wave OPA, we produce two-color squeezed vacuum with up to millions of photons per pulse. Our approach to registering this macroscopic quantum state is direct detection of a large number of transverse and longitudinal modes, which is achieved by making the detection time and area much larger than the coherence time and area, respectively. Using this approach, we obtain a record value of twin-beam squeezing for direct detection of bright squeezed vacuum. This makes direct detection of macroscopic squeezed vacuum a practical tool for quantum information applications.
Entangled Two-Photon Wave Packet in a Dispersive Medium
Alejandra Valencia,Maria V. Chekhova,Alexei Trifonov,Yanhua Shih
Physics , 2004, DOI: 10.1103/PhysRevLett.88.183601
Abstract: We report an experimental study of group-velocity dispersion effect on an entangled two-photon wavepacket, generated via spontaneous parametric down-conversion and propagating through a dispersive medium. Even in the case of using CW laser beam for pump, the biphoton wavepacket and the second-order correlation function spread significantly. The study and understanding of this phenomenon is of great importance for quantum information applications, such as quantum communication and distant clock synchronization.
Absolute Calibration of Analog Detectors by using Parametric Down Conversion
Giorgio Brida,Maria Chekhova,Marco Genovese,Alexander Penin,Maria Luisa Rastello,Ivano Ruo-Berchera
Physics , 2007,
Abstract: In this paper we report our systematic study of a promising absolute calibration technique of analog photo-detectors, based on the properties of parametric down conversion. Our formal results and a preliminary uncertainty analysis show that the proposed method can be effectively developed with interesting applications to metrology.
Absolute Quantum Efficiency Measurements by Means of Conditioned Polarization Rotation
Giorgio Brida,Maria Chekhova,Marco Genovese,Marco Gramegna,Leonid Krivitsky,Maria Luisa Rastello
Physics , 2005,
Abstract: We propose a new scheme for measuring the quantum efficiency of photon counting detectors by using correlated pho-tons. The measurement technique is based on a 90 rotation of the polarization of one photon member of a correlated pair produced by parametric down-conversion, conditioned on the detection of the other correlated photon after polarization selection. We present experimental results obtained with this scheme.
Two-Photon Polarization Interference for Pulsed SPDC in a PPKTP Waveguide
Malte Avenhaus,Maria V. Chekhova,Leonid A. Krivitsky,Gerd Leuchs,Christine Silberhorn
Physics , 2008, DOI: 10.1103/PhysRevA.79.043836
Abstract: We study the spectral properties of Spontaneous Parametric Down Conversion in a periodically poled waveguided structure of KTP crystal pumped by ultra-short pulses. Our theoretical analysis reveals a strongly multimode and asymmetric structure of the two-photon spectral amplitude for type-II SPDC. Experimental evidence, based on Hong-Ou-Mandel polarization interference with narrowband filtering, confirms this result.
Two-photon processes in faint biphoton fields
Dmitry V. Strekalov,Matt Stowe,Maria V. Chekhova,Jonathan P. Dowling
Physics , 2002, DOI: 10.1080/0950034021000038915
Abstract: The goal of this research is to determine and study a physical system that will enable a fast and intrinsically two-photon detector, which would be of interest for quantum information and metrology applications. We consider two types of two-photon processes that can be observed using a very faint, but quantum-correlated biphoton field. These are optical up-conversion and an external photoelectric effect. We estimate the correlation enhancement factor for the biphoton light compared to coherent light, report and discuss the preliminary experimental results.
Interferometric Bell-state preparation using femtosecond-pulse-pumped Spontaneous Parametric Down-Conversion
Yoon-Ho Kim,Maria V. Chekhova,Sergei P. Kulik,Morton H. Rubin,Yanhua Shih
Physics , 2001, DOI: 10.1103/PhysRevA.63.062301
Abstract: We present theoretical and experimental study of preparing maximally entangled two-photon polarization states, or Bell states, using femtosecond pulse pumped spontaneous parametric down-conversion (SPDC). First, we show how the inherent distinguishability in femtosecond pulse pumped type-II SPDC can be removed by using an interferometric technique without spectral and amplitude post-selection. We then analyze the recently introduced Bell state preparation scheme using type-I SPDC. Theoretically, both methods offer the same results, however, type-I SPDC provides experimentally superior methods of preparing Bell states in femtosecond pulse pumped SPDC. Such a pulsed source of highly entangled photon pairs is useful in quantum communications, quantum cryptography, quantum teleportation, etc.
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