Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Tunable control and use of the spectrum of photons in quantum optics applications

Alejandra Valencia, Martin Hendrych, Xiaojuan Shi, Noelia Gonzalez, Alessandro Ceré, Gabriel Molina‐Terriza, Juan P. Torres

Published Sep 11, 2007• 0 citations

Publisher

Abstract

One of the goals of quantum optics is to implement new sources of quantum light with tunable control of the relevant photonic properties. Here, we add to the toolkit of available techniques in quantum optics for the full control of the properties of quantum light, new strategies to manage the spectrum of photons, namely, type of frequency correlations, bandwidth and waveform. As a source of quantum light, spontaneous parametric downconversion (SPDC) is considered. Interestingly, the techniques presented might be used in any nonlinear medium and frequency band of interest. One of the schemes to control the frequency correlations makes use of light pulses with pulse-front tilt. The method is based on the proper tailoring of the group velocities of all the waves that interact in the nonlinear process, through the use of beams with angular dispersion. Noncollinear SPDC is the other strategy that is considered, since it allows mapping the spatial characteristics of the pump beam into the frequency properties of the downconverted photons.

DOI: 10.1117/12.733765

Related papers

Tunable control of the frequency correlations of entangled photons

Martin Hendrych, Michal Mičuda, Juan P. Torres

We experimentally demonstrate a new technique to control the type of frequency correlations of entangled photon pairs generated by spontaneous parametric downconversion. Frequency-correlated and frequency-anticorrelated photons are produced when a broadband pulse is used as a pump. The method is based on the control of the group velocities of the interacting waves and can be applied in any nonlinear medium and frequency band of interest.

arXiv:quant-ph/0612135Optics LettersAug 2, 200750 citations

Tailoring of the frequency correlations and the bandwidth of paired photons in noncollinear parametric downconversion

Alejandra Valencia, Alessandro Ceré, X. Shi +3 more

The bandwidth and the frequency correlations of quantum light can be considered as a resource for the implementation of new quantum information algorithms, and it should enable the applicability of quantum techniques not yet implemented. For that purpose, the control of the frequency correlations, and the bandwidth, of single and paired photons is an essential ingredient, since the optimum bandwidth, as well as the most appropriate type of frequency correlations for a specific quantum application, depend on the specific quantum information application under consideration. Here we elucidate and implement new strategies to tailor the frequency properties of quantum light. Such strategies, which are based on the use of non collinear spontaneous parametric down conversion (SPDC) configurations, include the generation of narrow and enhanced bandwidth quantum light, the control of the frequency correlations of paired photon, and the generation of heralded single photons with a high degree of purity from pairs of uncorrelated photons.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEAug 31, 20060 citations

Shaping the Waveform of Entangled Photons

Alejandra Valencia, Alessandro Ceré, Xiaojuan Shi +2 more

We demonstrate experimentally tunable control of the joint spectrum, i.e., waveform and degree of frequency correlations, of paired photons generated in spontaneous parametric down-conversion. This control is mediated by the spatial shape of the pump beam in type-I noncollinear configurations.

arXiv:0709.1810Physical Review LettersDec 14, 2007119 citations

Inverse design of spontaneous parametric downconversion for generation of high-dimensional qudits

Eyal Rozenberg, Aviv Karnieli, Ofir Yesharim +5 more

Spontaneous parametric downconversion (SPDC) in quantum optics is an invaluable resource for the realization of high-dimensional qudits with spatial modes of light. One of the main open challenges is how to directly generate a desirable qudit state in the SPDC process. This problem can be addressed through advanced computational learning methods; however, due to difficulties in modeling the SPDC process by a fully differentiable algorithm, progress has been limited. Here, we overcome these limitations and introduce a physically constrained and differentiable model, validated against experimental results for shaped pump beams and structured crystals, capable of learning the relevant interaction parameters in the process. We avoid any restrictions induced by the stochastic nature of our physical model and integrate the dynamic equations governing the evolution under the SPDC Hamiltonian. We solve the inverse problem of designing a nonlinear quantum optical system that achieves the desired quantum state of downconverted photon pairs. The desired states are defined using either the second-order correlations between different spatial modes or by specifying the required density matrix. By learning nonlinear photonic crystal structures as well as different pump shapes, we successfully show how to generate maximally entangled states. Furthermore, we simulate all-optical coherent control over the generated quantum state by actively changing the profile of the pump beam. Our work can be useful for applications such as novel designs of high-dimensional quantum key distribution and quantum information processing protocols. In addition, our method can be readily applied for controlling other degrees of freedom of light in the SPDC process, such as spectral and temporal properties, and may even be used in condensed-matter systems having a similar interaction Hamiltonian.

OpticaApr 29, 202233 citations

Quantum state engineering for spatial control of entangled photon pairs

Juan P. Torres, Lluís Torner

The two-photon state generated by spontaneous parametric down-conversion (SPDC) exhibit spatial entanglement embedded in the corresponding mode function. The control of the spatial characteristics of the generated two-photon state is an issue of paramount importance. For example, the spatial entanglement of the two down converted photons forms the basis of quantum imaging, and entanglement in orbital angular momentum has opened a new scenario for implementing multidimensional Hilbert spaces. We put forward several techniques to engineer the spatial structure of entangled two-photon states generated in SPDC. The first strategy we consider for spatial control of the quantum state makes use of the direct manipulation of the pump beam. This technique makes feasible to prepare arbitrary engineered entangled states in any d-dimensional Hilbert space. The second strategy is based on the proper preparation of the down-converting crystal itself, namely quantum state manipulation by quasi-phase-matching (QPM) engineering. We use properly designed transversely varying QPM gratings in nonlinear crystals.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEMar 14, 20052 citations

Spectrum Shaping of Paired Photons

Xiaojuan Shi

One 01 the main objectives of quantum optiCS is to prepare quantum light sources 'Nith the characteristics required lor various quantum optica ppllcallons. Pure single photons and entangled paired photons are two of the most 'Nidely used types of quantum tight. Single photons In a pure, well ellned quantum state may prove to be the building blocks lor future quantum technologies. These technologies promise enormous improvements ove heir ctasslcal counterparts In terms of speed or security. For eICample, in quantum inlormation processing, single photons may be used in quanturT ogic gales, playing the role of electrons in current electric circuits. Although light is all around us In all possible colors, polarizations and intensities, it I ICtremely difficult to get a single photon In a pure quantum state. On the other hand, 11 is relallvely easy to produce pairs of photons, and pure singl horons can be obtained from a two-photon source in a heralded way. Thus, generatlng paired photons with desired photonic properties becomes o'nE pf the cruciattasks in the research area 01 quantum optics and related applications. rrhe process of spontaneous parametric down-conversion (SPDC) is one 01 the most convenient ways to produce pairs 01 photons. In SPDC, a strons ump laser beam Is shone on a nonlinear crystal. Occasionally, a pump photon disappears and two new photons with lower energy are create imultaneously. The production of photon paIrs In the nonlinear crystal is probabilistic and the fact that the two photons are produced simultaneously I n advantage. The two photons can be taken apart and one 01 them can be used as a trigger 10 indicate (herald) the presence of the olher, thereb elllng us when a photon is ready to be used. These pairs of photons have special types 01 correlation In their color (frequency), in theIr spatial shape ndIor In Iheir polarization. For many applications, such as quantum cryptography, these types of correlation may be useful, but at the moment 0 enerating pure Single photons they are detrimental since they diminish the purity of the single photon. In this thesis, we are interested in the frequency properties 01 SPDC pairs of photons. and our main goal Is 10 demonstrate new methods 10 contre hese properties. The frequency properties ollhe photon pairs are described by its joint spectrum, which contains the information of the bandwidth, th wavalorm and the type of frequency correlation possessed by the two photons. n the first part of our work, two new toolklts are added to the current toolbox to manipulate the joint spectrum of photon pairs. One tool is called pulse ronHill' technique. This technique is based on the appropriate Introduction of angular dispersion into the interacting waves. The feasibitity of thi method is demonstrated by observing a sevenfold increase of the band;dth of photon pairs. The corresponding experiment has been accomplished b dding angular dispersion into a coItinear SPDC geometry, where the interacting waves propagate at the same direction. Also, we discuss Ih mplicalion 01 this method lor the generation 01 narrow temporal Fourier transform limited btphotons, and paired photons 'Nith high degree 0 ntangtement. The second tool is called spatial-to·spectral' mapping technique. This technique takes eHec! in a noncoUinear geomelry, in which caSE he pump beam and the down-<:onverted paired photons propagate at different directions. With this situatton, the spatial features of the pump beam 'Nil ~ Imprinted inlo the lrequency distribution 01 the new created photon pairs. We eICperimenlalty prove this method by shaping the waveform, and tunin he types ollrequency correlation 01 the dO'M'l-converted two photons. n addition, we propose a new scheme to fully control the Joint spectrum ollhe pholon pairs by combining the above two discussed techniques. In thi proposal, angular dispersion is introduced into a noncollinear SPDC geometry. This opens a new way to obtain pure single photons 'Nith tunabl band'Nidth. Another topic discussed in this thesis is the exploration of more compact quantum light sources 'Nith versatile characteristics. We describe an SPDC !WO-photon source by using Brag9 reflection wavegulde (BAW) in AI .Gah. As material as down-converting material. Here, the nonlinear proces happens between a pump beam in 8 Bragg refleclion wavegulde mode, and down-converted photon pairs in total internal rellection (TtA) mode. Th ~aveguide dispersion properties can be largely modified by implementing different ridge sizes. and this allows the described monolithic source 10 oHe Ignificant control over the process band'Nidth. We numerically demonstrate the possibility 01 tuning the bandwidth 01 the photon pairs between 1 n~ nd 450 nm with the same waler structure. The results presented in this part have been obtained as a result 01 the collaboration ;th Prol. Amr S. Helmy and his PhD student Payam Abolghasem from University of Toronto. In particular, the programs used lor the presented simulations have bee developed by the University of Toronto leam. o summarize, In this thesis, we add new elements to the current ways 01 engineering quantum light sources. Two readily be used methods to enginee he spectrum of the photon pairs are presented. Particularly, new routes are provided to get pure heralded single photons and narrow tempora biphoton. In addil!on, a compact monolithic two-photon source ;th tunable bandwidth control Is Investigated, which could be very promIsing for furthe pOrlormance of various quantum applications towards reality. Uoc I data Barcelona, 2009·11-16 Signature

Jan 1, 20091 citation