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## Purity and entanglement of two-photon polarization states generated by spontaneous parametric down-conversion

BERNARDES, Nadja K.; MOURA, A. G. da Costa; MONKEN, C. H.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
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We elucidate the dependence of purity and entanglement of two-photon states generated by spontaneous parametric down-conversion on the parameters of the source, such as crystal length, pump beam divergence, frequency bandwidth, and detectors angular aperture. The effect of crystal anisotropy is taken into account. Numerical simulations are presented for two types of commonly used source configurations. (C) 2009 Elsevier B.V. All rights reserved.; CNPq - Conselho Nacional de Desenvolvimento Cientifico a Tecnologico; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Instituto do Milenio de Informacao Quantica; Instituto do Milenio de Informacao Quantica; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); CAPES; Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG); FAPEMIG

## Geração de harmônicos de pulsos laser de femtossegundo pela técnica de conversão de frequência em capilares preenchidos com gases nobres; Harmonics generation of femtosecond laser pulses by the technique of frequency conversion in noble gas filled capillaries

Siqueira, Jonathas de Paula
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
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O propósito principal desta tese foi a implementação e estudo da geração de pulsos laser de femtossegundos em comprimentos de onda curtos (ultravioleta profundo, ultravioleta de vácuo e ultravioleta extremo) pela técnica de conversão de frequência em capilar preenchido com gás nobre. Esta técnica de conversão de frequência tem feito diversas contribuições nas últimas décadas para o avanço da geração de pulsos laser ultracurtos nesta região espectral. O desenvolvimento de tais fontes de luz coerente possui importantes implicações nos estudos de espectroscopia resolvida no tempo em átomos, moléculas e materiais. Através da implementação da técnica de conversão de frequência com casamento de fase em capilar preenchido com gás argônio, foi possível a obtenção de pulsos de femtossegundos centrados em 260 nm e 195 nm utilizando um sistema laser amplificado Ti: safira (780 nm, 1.5 mJ, 43 fs, 1 KHz). Estes comprimentos de onda correspondem, respectivamente, aos terceiro e quarto harmônicos da frequência fundamental do laser utilizado. Pulsos centrados em 260 nm com excelente perfil espacial, energias da ordem de microjoules e durações temporais tão curtas quanto 18 fs, possibilitadas pela recompressão por um par de prismas...

## A unified description of sum frequency generation, parametric down conversion and two-photon fluorescence

Roslyak, Oleksiy; Mukamel, Shaul
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.059697%
A superoperator non-equilibrium Green’s function formalism is presented for computing nonlinear optical processes involving any combination of classical and quantum optical modes. Closed correlation-function expressions based on superoperator time-ordering are derived for the combined effects of causal response and non-causal spontaneous fluctuations. Coherent three wave mixing (sum frequency generation and parametric down conversion) involving one and two quantum optical modes, respectively, are compared with their incoherent counterparts: two-photon-induced fluorescence and two-photon-emitted fluorescence.

## Coherence properties of the entangled two-photon field produced by parametric down-conversion

Jha, Anand Kumar (1978 - ); Boyd, Robert W. (1948 - )
Fonte: University of Rochester. Publicador: University of Rochester.
Tipo: Tese de Doutorado Formato: Number of Pages:xiii, 133 leaves
ENG
Relevância na Pesquisa
68.370254%
Thesis (Ph. D.)--University of Rochester. Institute of Optics, 2010.; Parametric down-conversion is a second-order nonlinear optical process in which a pump photon breaks up into two separate photons known as the signal photon and the idler photon. The constraints of energy and momentum conservation render the signal and idler photons entangled in several different variables including time and energy, position and transverse momentum, and angular position and orbital angular momentum. Because of these correlations, the down-converted signal and idler photons can be described adequately only as a single, two-photon system. In this thesis, we present our theoretical and experimental studies of the coherence properties of the down-converted, entangled two-photon fields, through two-photon interference effects in temporal, spatial and angular domains. First of all, we study the temporal coherence properties of the down-converted two-photon fields, in the limit in which the frequency bandwidth of the pump field is much narrower than that of the down-converted field. We present a formalism to completely characterize temporal two-photon interference effects in terms of the variations of two length parameters|called the two-photon path length difference and the two-photon path-asymmetry length difference|which we construct using the six different length parameters that a general two-photon interference experiment involves. Next...

## Generation of Bessel beams by parametric frequency doubling in annular nonlinear periodic structures

Saltiel, Solomon; Krolikowski, Wieslaw; Neshev, Dragomir; Kivshar, Yuri
Tipo: Journal article; Published Version Formato: 7 pages
Relevância na Pesquisa
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We analyze the second-harmonic generation in two-dimensional photonic structures with radially periodic domains created by poling of a nonlinear quadratic crystal. We demonstrate that the parametric conversion of the Gaussian fundamental beam propagating along the axis of the annular structure leads to the axial emission of the second-harmonic field in the form of the radially polarized first-order Bessel beam.

## Generation of conical second harmonic waves by nonlinear Bragg diffraction in two-dimensional nonlinear photonic structures

Saltiel, Solomon; Neshev, Dragomir; Krolikowski, Wieslaw; Fischer, Robert; Arie, Ady; Kivshar, Yuri
Fonte: SPIE - The International Society for Optical Engineering Publicador: SPIE - The International Society for Optical Engineering
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
57.72792%
We generate conical second-harmonic waves through the parametric frequency conversion in a two-dimensional annular, periodically poled nonlinear photonic structure under the transverse excitation with a fundamental Gaussian beam. We explain the effects ob

## Phase matching in nonlinear c(2) photonic crystals

Saltiel, Solomon M; Kivshar, Yuri
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
57.72792%
We analyze harmonic generation in a two-dimensional (2D) χ(2) photonic crystal and demonstrate the possibility of multiple phase matching and multicolor parametric frequency conversion. We suggest a new type of photonic structure to achieve simultaneous

## Theory of quantum frequency conversion and type-II parametric down-conversion in the high-gain regime

Christ, Andreas; Brecht, Benjamin; Mauerer, Wolfgang; Silberhorn, Christine
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.303765%
Frequency conversion (FC) and type-II parametric down-conversion (PDC) processes serve as basic building blocks for the implementation of quantum optical experiments: type-II PDC enables the efficient creation of quantum states such as photon-number states and Einstein-Podolsky-Rosen-states (EPR-states). FC gives rise to technologies enabling efficient atom-photon coupling, ultrafast pulse gates and enhanced detection schemes. However, despite their widespread deployment, their theoretical treatment remains challenging. Especially the multi-photon components in the high-gain regime as well as the explicit time-dependence of the involved Hamiltonians hamper an efficient theoretical description of these nonlinear optical processes. In this paper, we investigate these effects and put forward two models that enable a full description of FC and type-II PDC in the high-gain regime. We present a rigorous numerical model relying on the solution of coupled integro-differential equations that covers the complete dynamics of the process. As an alternative, we develop a simplified model that, at the expense of neglecting time-ordering effects, enables an analytical solution. While the simplified model approximates the correct solution with high fidelity in a broad parameter range...

## Third-order spontaneous parametric down-conversion in thin optical fibers as a photon-triplet source

Corona, Maria; Garay-Palmett, Karina; U'Ren, Alfred
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.059697%
We study the third order spontaneous parametric down conversion (TOSPDC) process, as a means to generate entangled photon triplets. Specifically, we consider thin optical fibers as the nonlinear medium to be used as the basis for TOSPDC in configurations where phase matching is attained through the use of more than one fiber transverse modes. Our analysis in this paper, which follows from our earlier paper Optics Letters 36, 190 (2011), aims to supply experimentalists with the details required in order to design a TOSPDC photon-triplet source. Specifically, our analysis focuses on the photon triplet state, on the rate of emission, and on the TOSPDC phasematching characteristics for the cases of frequency degenerate and frequency nondegenerate TOSPDC.

## Controllable Frequency Entanglement via Auto-Phase-Matched Spontaneous Parametric Down-Conversion

Walton, Zachary D.; Booth, Mark C.; Sergienko, Alexander V.; Saleh, Bahaa E. A.; Teich, Malvin C.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.24098%
A new method for generating entangled photons with controllable frequency correlation via spontaneous parametric down-conversion (SPDC) is presented. The method entails initiating counter-propagating SPDC in a single-mode nonlinear waveguide by pumping with a pulsed beam perpendicular to the waveguide. The method offers several advantages over other schemes, including the ability to generate frequency-correlated photon pairs regardless of the dispersion characteristics of the system. Numerical evidence demonstrates the improvement provided by this source in the special case of frequency-correlated two-photon states.; Comment: 5 pages, 4 figures; recalculated the bold visibility curve in Fig. 4 for a GaAs (instead of KTP) waveguide--conclusions unchanged; accepted for publication in Physical Review A

## Realization of microwave amplification, attenuation, and frequency conversion using a single three-level superconducting quantum circuit

Zhao, Yan-Jun; Ding, Jiang-Hao; Peng, Z. H.; Liu, Yu-xi
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.263037%
Using different configurations of applied strong driving and weak probe fields, we find that only a single three-level superconducting quantum circuit (SQC) is enough to realize amplification, attenuation and frequency conversion of microwave fields. Such a three-level SQC has to possess $\Delta$-type cyclic transitions. Different from the parametric amplification (attenuation) and frequency conversion in nonlinear optical media, the real energy levels of the three-level SQC are involved in the energy exchange when these processes are completed. We mainly show the efficiencies of the amplification and the frequency conversion for different types of driving fields. Our study provides a new method to amplify (attenuate) microwave, realize frequency conversion, and also lays a foundation for generating single or entangled microwave photon states using a single three-level SQC.

## Mapping of periodically poled crystals via spontaneous parametric down-conversion

Kitaeva, G. Kh.; Tishkova, V. V.; Naumova, I. I.; Penin, A. N.; Kang, C. H.; Tang, S. H.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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A new method for characterization of periodically poled crystals is developed based on spontaneous parametric down-conversion. The method is demonstrated on crystals of Y:LiNbO3, Mg:Y:LiNbO3 with non-uniform periodically poled structures, obtained directly under Czochralski growth procedure and designed for application of OPO in the mid infrared range. Infrared dispersion of refractive index, effective working periods and wavelengths of OPO were determined by special treatment of frequency-angular spectra of spontaneous parametric down-conversion in the visible range. Two-dimensional mapping via spontaneous parametric down-conversion is proposed for characterizing spatial distribution of bulk quasi-phase matching efficiency across the input window of a periodically poled sample.; Comment: 19 pages, 6 figures

## Far detuned mid-infrared frequency conversion via normal dispersion modulation instability in chalcogenide microwire

Godin, Thomas; Combes, Yves; Ahmad, Raja; Rochette, Martin; Sylvestre, Thibaut; Dudley, John M.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
58.059697%
We report the observation of modulation instability in the mid-infrared spectral region by pumping a hybrid polymer-chalcogenide optical microwire with a femtosecond optical parametric oscillator operating at 2.6 {\mu}m. It is further shown that this modulation instability occurs in the normal dispersion regime through negative fourth-order dispersion and leads to far detuned parametric frequency conversion at 2 {\mu}m and 3.5 {\mu}m, despite the presence of a strong absorption band around 2.8 {\mu}m. Stochastic nonlinear Schr\"odinger equation simulations of mid-infrared modulation instability are in excellent agreement with experiments.

## A versatile design for resonant guided-wave parametric down-conversion sources for quantum repeaters

Brecht, Benjamin; Luo, Kai-Hong; Herrmann, Harald; Silberhorn, Christine
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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Quantum repeaters - fundamental building blocks for long-distance quantum communication - are based on the interaction between photons and quantum memories. The photons must fulfil stringent requirements on central frequency, spectral bandwidth and purity in order for this interaction to be efficient. We present a design scheme for monolithically integrated resonant photon-pair sources based on parametric down-conversion in nonlinear waveguides, which facilitate the generation of such photons. We investigate the impact of different design parameters on the performance of our source. The generated photon spectral bandwidths can be varied between several tens of MHz up to around $1\,$GHz, facilitating an efficient coupling to different memories. The central frequency of the generated photons can be coarsely tuned by adjusting the pump frequency, poling period and sample temperature and we identify stability requirements on the pump laser and sample temperature that can be readily fulfilled with off-the-shelve components. We find that our source is capable of generating high-purity photons over a wide range of photon bandwidths. Finally, the PDC emission can be frequency fine-tuned over several GHz by simultaneously adjusting the sample temperature and pump frequency. We conclude our study with demonstrating the adaptability of our source to different quantum memories.; Comment: 10 pages...

## Entanglement-preserving frequency conversion in cold atoms

Gogyan, A.; Malakyan, Yu.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.200054%
We propose a method that enables efficient frequency conversion of quantum information based on recently demonstrated strong parametric coupling between two single-photon pulses propagating in a slow-light atomic medium at different group velocities. We show that an incoming single-photon state is efficiently converted into another optical mode in a lossless and shape-conserving manner. The persistence of initial quantum coherence and entanglement within frequency conversion is also demonstrated. We first illustrate this result for the case of small frequency difference of converted photons, and then discuss the modified scheme for conversion of photon wavelengths in different spectral ranges. Finally we analyze the generation of a narrow-band single-photon frequency-entangled state.; Comment: minor corrections compared to the published version, 7 pages, 5 figures

## Towards quantum frequency combs: boosting the generation of highly nonclassical light states by cavity-enhanced parametric down-conversion at high repetition rates

Zavatta, Alessandro; Parigi, Valentina; Bellini, Marco
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.12619%
We demonstrate the generation of multi-photon quantum states of light by cavity-enhanced parametric down-conversion in the high-repetition-rate pulsed regime. An external enhancement cavity resonant with the spectral comb of modes of a mode-locked pump laser provides a coherent build-up of the pump intensity and greatly enhances the parametric gain without sacrificing its high repetition rate and comb structure. We probe the parametric gain enhancement by the conditional generation and tomographic analysis of two-photon Fock states. Besides its potential impact to efficiently generate highly-nonclassical or entangled multi-photon states in many existing experimental setups, this scheme opens new and exciting perspectives towards the combination of quantum and comb technologies for enhanced measurements and advanced quantum computation protocols.; Comment: 5 pages 3 figures; updated with major additions, added references, and changed title. Accepted for publication in Physical Review A

## Modal, Spectral, and Polarization Entanglement in Guided-Wave Parametric Down-Conversion

Saleh, Mohammed F.; Saleh, Bahaa E. A.; Teich, Malvin Carl
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.210786%
We examine the modal, spectral, and polarization entanglement properties of photon pairs generated in a nonlinear, periodically poled, two-mode waveguide (1-D planar or 2-D circular) via nondegenerate spontaneous parametric down-conversion. Any of the possible degrees of freedom -- mode number, frequency, or polarization -- can be used to distinguish the down-converted photons while the others serve as attributes of entanglement. Distinguishing the down-converted photons based on their mode numbers enables us to efficiently generate spectral or polarization entanglement that is either narrowband or broadband. On the other hand, when the generated photons are distinguished by their frequencies in a Type-0 process, modal entanglement turns out to be an efficient alternative to polarization entanglement. Moreover, modal entanglement in Type-II down-conversion may be used to generate a doubly entangled state in frequency and polarization.; Comment: 10 pages, 9 figures, journal paper

## Storage and retrieval of nonclassical photon pairs and conditional single photons generated by parametric down-conversion process

Akiba, K.; Kashiwagi, K.; Arikawa, M.; Kozuma, M.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
48.171924%
Storage and retrieval of parametric down-conversion (PDC) photons are demonstrated with electromagnetically induced transparency (EIT). Extreme frequency filtering is performed for THz order of broadband PDC light and the frequency bandwidth of the light is reduced to MHz order. Storage and retrieval procedures are carried out for the frequency filtered PDC photons. Since the filtered bandwidth [full width at half-maximum (FWHM) = 9 MHz] is within the EIT window (FWHM = 12.6 MHz), the flux of the PDC light is successfully stored and retrieved. The nonclassicality of the retrieved light is confirmed by using photon counting method, where the classical inequality which is only satisfied for classical light fields is introduced. Since the PDC photons can be utilized for producing the single photon state conditionally, storage and retrieval procedures are also performed for the conditional single photons. Anti-correlation parameter used for checking the property of single photon state shows the value less than 1, which means the retrieved light is in a non-classical region.; Comment: 4 figures

## Time-frequency quantum process tomography of parametric down-conversion

Avenhaus, Malte; Brecht, Benjamin; Laiho, Kaisa; Silberhorn, Christine
Tipo: Artigo de Revista Científica