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Search Results: 1 - 10 of 199703 matches for " Maria V. 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.
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.
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.
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.
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.
Experimental Entanglement Concentration and Universal Bell-state Synthesizer
Yoon-Ho Kim,Sergei P. Kulik,Maria V. Chekhova,Warren P. Grice,Yanhua Shih
Physics , 2002, DOI: 10.1103/PhysRevA.67.010301
Abstract: We report a novel Bell-state synthesizer in which an interferometric entanglement concentration scheme is used. An initially mixed polarization state from type-II spontaneous parametric down-conversion becomes entangled after the interferometric entanglement concentrator. This Bell-state synthesizer is universal in the sense that the output polarization state is not affected by spectral filtering, crystal thickness, and, most importantly, the choice of pump source. It is also robust against environmental disturbance and a more general state, partially mixed$-$partially entangled state, can be readily generated as well.
Compensation of anisotropy effects in the generation of two-photon light
Andrea Cavanna,Angela M. Pérez,Felix Just,Maria V. Chekhova,Gerd Leuchs
Physics , 2014, DOI: 10.1364/OE.22.009983
Abstract: We analyse a method to compensate for anisotropy effects in the spatial distribution of parametric down-conversion (PDC) radiation in bulk crystals. In this method, a single nonlinear crystal is replaced by two consecutive crystals with opposite transverse walk-off directions. We implement a simple numerical model to calculate the spatial distribution of intensity and correlations, as well as the Schmidt mode structure, with an account for the anisotropy. Experimental results are presented which prove the validity of both the model and the method.
Raman-free, noble-gas-filled PCF source for ultrafast, very bright twin-beam squeezed vacuum
Martin A. Finger,Timur Sh. Iskhakov,Nicolas Y. Joly,Maria V. Chekhova,Philip St. J. Russell
Physics , 2015, DOI: 10.1103/PhysRevLett.115.143602
Abstract: We report a novel source of twin beams based on modulational instability in high-pressure argon-filled hollow-core kagom\'e-style photonic-crystal fibre. The source is Raman-free and manifests strong photon-number correlations for femtosecond pulses of squeezed vacuum with a record brightness of ~2500 photons per mode. The ultra-broadband (~50 THz) twin beams are frequency tunable and contain one spatial and less than 5 frequency modes.
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