1,721,096 research outputs found
Improved Visibility of Spectral Two-photon Quantum Interference Introduced by Multiphoton Components
No full textSpectral two-photon quantum interference between a thermal field and a heralded state is studied theoretically and experimentally, demonstrating visibility enhancements as a result of the contribution of multiphoton components within the heralded photon state
Entanglement of PDC photon pairs
No full textWe investigate the spatio-temporal structure of the biphoton entanglement in parametric down-conversion (PDC) and we demonstrate its non-factorable X-shaped geometry. Such a structure gives access to the ultrabroad bandwidth of PDC, and can be exploited to achieve a biphoton temporal localization in the femtosecond range. This extreme localization is conditioned by our ability to resolve the photon positions in the source near field. The nonfactorability opens the possibility of tailoring the temporal entanglement by acting on the spatial degrees of freedom of twin photons. We also put in evidence distinctive features that characterize type II with respect to type I PD
Quantum spatial correlations in parametric down-conversion and detection of faint images
No full textA recent experiment has demonstrated the quantum nature of spatial fluctuations in the high gain regime of parametric down-conversion. We show theoretically and numerically that, by exploiting the local character of these spatial correlations, it is possible to image weak amplitude objects with a sensitivity beyond the standard quantum limit
Complete pump depletion by autoresonant wave mixing in nonuniform second order media
No full textWe propose an analytical theory for the autoresonant phase matching of parametric processes in generic nonuniform χ(2) media. We determine the necessary criteria for achieving complete pump depletion in terms of the physical experimental parameters. © 2013 The Optical Society
X-entanglement: the non-factorable spatio-temporal structure of biphoton correlation
No full textIn this work we turn our attention to the genuine quantum properties of PDC, and we demonstrate the hyperbolic
geometry underlying the spatio-temporal structure of the PDC entanglement and its non-factorability with
respect to space and time [1,2]. As for the macroscopic X-waves, the X-shape of the biphoton correlation is
imposed by the phase-matching mechanism governing the PDC process, and following this analogy we coined
the name of X-entanglement
[1] A. Gatti, E. Brambilla, L. Caspani, O. Jedrkiewicz, and L.A. Lugiato, Phys. Rev. Lett. 102, 223601 (2009) ;
e-print arXiv:0812.3533v1
[2] L. Caspani, E. Brambilla and A. Gatti, Tailoring the spatio-temporal structure of biphoton entanglement in
type I PDC , Phys. Rev A, 81, 033808 (2010
Complete energy conversion by autoresonant three-wave mixing in nonuniform media
No full textResonant three-wave interactions appear in many fields of physics e. g. nonlinear optics, plasma physics, acoustics and hydrodynamics. A general theory of autoresonant three-wave mixing in a nonuniform medium is derived analytically and demonstrated numerically. It is shown that due to the medium nonuniformity, a stable phase-locked evolution is automatically established. For a weak nonuniformity, the efficiency of the energy conversion between the interacting waves can reach almost 100%. One of the potential applications of our theory is the design of highly-efficient optical parametric amplifiers. (C) 2013 Optical Society of Americ
Complete pump depletion by autoresonant second harmonic generation in a nonuniform medium
No full textIn this paper, we develop for the first time to our knowledge an analytical theory of second harmonic generation (SHG) in a generic nonuniform. chi((2)) medium. It is shown that by varying the properties of the medium gradually enough, the system can enter an autoresonant state in which the phases of the fundamental pump and of the generated second harmonic wave are locked. The effect of autoresonance allows efficient transfer of energy between the waves and, due to the continuous phase-locking in the system, all the energy of the pump could be converted to the second harmonic. Simple closed-form expressions for the waves amplitudes as a function of the longitudinal coordinate are derived, and an explicit criterion for the stability of the autoresonant state is obtained. Our analytical theory is compared to the numerical solution of the coupled mode equations, which are found to be in excellent agreement with each other. The analytical closed-form expressions that we derive could be very useful for practical design of SHG devices with increased performances, such as highly efficient, wideband frequency converters. (C) 2013 Optical Society of Americ
Intra-cavity singly-resonant OPO pumped by a visible VECSEL for low-noise down-conversion to 1.55 μm
No full textWe report the first OPO pumped intra-cavity by an AlGalnP-based VECSEL. The continuous- wave. single-frequency OPO is pumped at 690.6 nm, operates with down-conversion efficiency of 68.7%, and is free of relaxation oscillations: of interest for generation of quantum light states
Tailoring the spatiotemporal structure of biphoton entanglement in type-I parametric down-conversion
No full textWe investigate the spatiotemporal structure of the biphoton entangled state produced by parametric down-conversion (PDC) at the output face of the nonlinear crystal. We analyze the geometry of biphoton correlation for different gain regimes (from ultralow to high), different crystal lengths, and different tuning angles of the crystal. While for collinear or quasicollinear phase matching a X-shaped geometry, nonfactorizable in space and time, dominates, in the highly noncollinear conditions we observe a remarkable transition to a factorizable geometry. We show that the geometry of spatiotemporal correlation is a consequence of the angle-frequency relationship imposed by phase matching and that the fully spatiotemporal analysis provides a key to control the spatiotemporal properties of the PDC entangled state and in particular to access a biphoton localization in time and space in the femtosecond and micrometer range, respectively
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