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Artoni M.,European Laboratory for Nonlinear Spectroscopy LENS | Artoni M.,CNR Institute of Neuroscience | Artoni M.,University of Brescia | Zavatta A.,CNR Institute of Neuroscience
Physical Review Letters

Phase-resonant closed-loop optical transitions can be engineered to achieve broadly tunable light phase shifts. Such a novel phase-by-phase control mechanism does not require a cavity and is illustrated here for an atomic interface where a classical light pulse undergoes radian level phase modulations all-optically controllable over a few micron scale. It works even at low intensities and hence may be relevant to new applications of all-optical weak-light signal processing. © 2015 American Physical Society. Source

Fedyanin D.Y.,Moscow Institute of Physics and Technology | Agio M.,CNR Institute of Neuroscience | Agio M.,European Laboratory for Nonlinear Spectroscopy LENS | Agio M.,Center for Quantum Science and Technology in Arcetri | Agio M.,University of Siegen
New Journal of Physics

The recently demonstrated electroluminescence of color centers in diamond makes them one of the best candidates for room temperature single-photon sources. However, the reported emission rates are far off what can be achieved by state-of-the-art electrically driven epitaxial quantum dots. Since the electroluminescence mechanism has not yet been elucidated, it is not clear to what extent the emission rate can be increased. Here we develop a theoretical framework to study single-photon emission from color centers in diamond under electrical pumping. The proposed model comprises electron and hole trapping and releasing, transitions between the ground and excited states of the color center as well as structural transformations of the center due to carrier trapping. It provides the possibility to predict both the photon emission rate and the wavelength of emitted photons. Self-consistent numerical simulations of the single-photon emitting diode based on the proposed model show that the photon emission rate can be as high as 100 kcounts s-1 at standard conditions. In contrast to most optoelectronic devices, the emission rate steadily increases with the device temperature achieving of more than 100 Mcount s-1 at 500 K, which is highly advantageous for practical applications. These results demonstrate the potential of color centers in diamond as electrically driven non-classical light emitters and provide a foundation for the design and development of single-photon sources for optical quantum computation and quantum communication networks operating at room and higher temperatures. © 2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. Source

Muniz-Miranda M.,University of Florence | Muniz-Miranda M.,European Laboratory for Nonlinear Spectroscopy LENS
Applied Catalysis B: Environmental

Nitrophenols represent common environmental pollutants because of their toxicity and resistance to microbial degradation. In the present work the SERS (surface-enhanced Raman scattering) spectroscopy has been applied to Ag/titania colloidal nanocomposites to monitor the catalytic reduction of 4-nitrophenol under UV irradiation and identify the reaction products. © 2013 Elsevier B.V. Source

Volkov V.,Max Planck Institute for Polymer Research | Righini R.,European Laboratory for Nonlinear Spectroscopy LENS
Physical Chemistry Chemical Physics

While tetracyclines are in active medical use, their bioactive atomic compositions are still questionable. Here, we investigate the structural properties of neutral tetracycline in dimethyl sulfoxide-the environment used often to mimic the environment in vivo. We compare the measured linear and nonlinear infrared spectra to those calculated for a collection of stable and energetically plausible tautomers, and describe the structurally sensitive off-diagonal peaks using anharmonicities of the normal modes. The comparison of experimental and theoretical 2DIR spectra is consistent with the numerical predictions of statistical thermodynamics on the relative weights of possible tautomers. In result, we provide the systematic account of the structural realizations of neutral tetracycline in DMSO. © 2014 the Owner Societies. Source

Wu J.-H.,Northeast Normal University | Artoni M.,European Laboratory for Nonlinear Spectroscopy LENS | Artoni M.,University of Brescia | La Rocca G.C.,Normal School of Pisa
Physical Review A - Atomic, Molecular, and Optical Physics

Lossy atomic photonic crystals can be suitably tailored so that the real and imaginary parts of the susceptibility are, respectively, an odd and an even function of position. Such a parity-time (PT) space antisymmetry in the susceptibility requires neither optical gain nor negative refraction, but is rather attained by a combined control of the spatial modulation of both the atomic density and their dynamic level shift. These passive photonic crystals made of dressed atoms are characterized by a tunable unidirectional reflectionlessness accompanied by an appreciable degree of transmission. Interestingly, such peculiar properties are associated with non-Hermitian degeneracies of the crystal scattering matrix, which can then be directly observed through reflectivity measurements via a straightforward phase modulation of the atomic dynamic level shift and even off resonance. © 2015 American Physical Society. Source

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