Now showing items 21-40 of 75

    • Efficient generation of new optical wavelengths by means of second harmonic generation in AlGaAs Bragg reflection waveguides 

      Valles Mari, Adam (Universitat Politècnica de Catalunya, 2011-09-19)
      Master thesis (pre-Bologna period)
      Open Access
      English: In this project has been designed and implemented a setup to produce the nonlinear process of the second harmonic generation (SHG) in Bragg reflection waveguides (BRW). Starting with the adjustment of a tunable ...
    • Efficient heralding of polarization-entangled photons from type-0 and type-II spontaneous parametric downconversion in periodically poled KTiOPO 4 

      Steinlechner, Fabian; Gilaberte, Marta; Jofre, Marc; Scheidl, Thomas; Pérez Torres, Juan; Pruneri, Valerio; Ursin, Rupert (2014-09-01)
      Article
      Restricted access - publisher's policy
      Ultrabright sources of entangled photon pairs with high heralding efficiency are an important step in the pursuit of high-bit-rate entanglement-base quantum key distribution, as well as an enabling tool for loss-sensitive ...
    • Entangled Photon Source for Single Molecule Microscopy 

      Abbasi Zargaleh, Soroush (Universitat Politècnica de Catalunya, 2013-02-11)
      Master thesis
      Open Access
      [ANGLÈS] This paper presents experimental implementation of highly correlated photons for single molecules microscopy application. We designed and built a Type-II Spontaneous Parametric Down Conversion (SPDC) photon pair ...
    • Entanglement and Nonlocality are Inequivalent for Any Number of Parties 

      Augusiak, R.; Demianowicz, M.; Tura, J.; Acín, Antonio (APS, 2015-07-15)
      Article
      Open Access
      Understanding the relation between nonlocality and entanglement is one of the fundamental problems in quantum physics. In the bipartite case, it is known that these two phenomena are inequivalent, as there exist entangled ...
    • Flux enhancement of photons entangled in orbital angular momentum 

      Palacios, Silvana; León Montiel, R.D.J.; Hendrych, Martin; Valencia, Alejandra; Pérez Torres, Juan (2011-07-18)
      Article
      Restricted access - publisher's policy
      Entangled photons are generally collected by detection systems that select their certain spatial modes, for example using single-mode optical fibers. We derive simple and easy-to-use expressions that allow us to maximize ...
    • Fragmented condensation in Bose–Hubbard trimers with tunable tunnelling 

      Gallemí, A.; Guilleumas, M.; Martorell, J.; Mayol, R.; Polls, A.; Juliá-Díaz, Bruno (IOP, 2015-07-15)
      Article
      Open Access
      We consider a Bose–Hubbard (BH) trimer, i.e. an ultracold Bose gas populating three quantum states. The latter can be either different sites of a triple-well potential or three internal states of the atoms. The bosons can ...
    • Frequency conversion of structured light 

      Steinlechner, Fabian; Hermosa, Nathaniel; Pruneri, Valerio; Pérez Torres, Juan (Macmillan Publishers, 2016-02-15)
      Article
      Open Access
      Coherent frequency conversion of structured light, i.e. the ability to manipulate the carrier frequency of a wave front without distorting its spatial phase and intensity profile, provides the opportunity for numerous novel ...
    • Generation of polarization entangled photon pairs in Bragg reflection waveguides 

      Vallés Marí, Adam (Universitat Politècnica de Catalunya, 2012-09-06)
      Master thesis
      Open Access
      [ANGLÈS] We report the observation of polarization entangled photon pairs generated by means of type-II spontaneous parametric down-conversion (SPDC) within an AlGaAs Bragg reflection waveguide (BRW). Even though SPDC in ...
    • Globally-linked vortex clusters 

      Crasovan, L C; Vekslerchik, V; Mihalache, Dumitru; Pérez Torres, Juan; Perez-Garcia, V M; Torner Sabata, Lluís (Kluwer, 2004-09-30)
      Part of book or chapter of book
      Restricted access - publisher's policy
      We show the existence of a rich variety of fully stationary vortex structures made of an increasing number of vortices nested in paraxial wave fields confined by symmetric and asymmetric harmonic trapping potentials in ...
    • Harnessing magneto-electric interference to direct light emission with a split-ring resonator 

      Hancu, Ion Michael (Universitat Politècnica de Catalunya, 2012-09-03)
      Master thesis
      Open Access
      [ANGLÈS] Here we show that a split-ring resonator, a structure widely known for its magnetic response at optical frequencies, can be used as a robust, unidirectional and broadband nanoantenna. By customizing its dimensions ...
    • Improved Quantum Magnetometry beyond the Standard Quantum Limit 

      Brask, J. B.; Chaves, R.; Kołodyński, J. (APS, 2015-07-22)
      Article
      Open Access
      Under ideal conditions, quantum metrology promises a precision gain over classical techniques scaling quadratically with the number of probe particles. At the same time, no-go results have shown that generic, uncorrelated ...
    • Insights into Q2Qbar2 states from an effective perspective 

      Ametller Congost, Lluís; Talavera Sánchez, Pedro (American Physical Society, 2015-10-07)
      Article
      Open Access
      We discuss the two-photon coupling of the lightest scalar meson on the basis of an extension of χPT. Using low-energy data on the pion form factor and the γγ→π+π−(π0π0) cross sections as inputs, we find Γ(σ→γγ)≅0.126  keV. ...
    • Laser frequency stabilization to excited Rydberg transitions using electromagnetically induced transparency 

      Grimau Puigibert, Marcel·lí (Universitat Politècnica de Catalunya, 2012-09-10)
      Master thesis
      Open Access
      [ANGLÈS] Rydberg atoms with principal quantum number n>>1 have extraordinary atomic properties including tunable long range dipole-dipole interactions that lead to the so called Rydberg blockade. Atoms excited to these ...
    • Locality of temperature in spin chains 

      Hernández-Santana, Senaida; Riera, Arnau; Hovhannisyan, Karen V.; Perarnau-Llobet, Martí; Tagliacozzo, Luca (IOP, 2015-08-18)
      Article
      Open Access
      In traditional thermodynamics, temperature is a local quantity: a subsystem of a large thermal system is in a thermal state at the same temperature as the original system. For strongly interacting systems, however, the ...
    • Long-lived spin coherence of indirect excitons in GaAs coupled quantum wells 

      Beian, Mussie; Alloing, Mathieu; Cambril, Edmond; Gomez Carbonell, Carmen; Osmond, Johann; Lemaître, Aristide; Dubin, François (IOP, 2015-04-30)
      Article
      Open Access
      We study spatially indirect excitons confined in a symmetric GaAs double quantum well. We show that the spin polarisation of very dilute gases can be optically imprinted, in both pure and superposition states. In the regime ...
    • Measurement of noise-induced loss of polarization coherence 

      Jiménez Machado, Gerard (Universitat Politècnica de Catalunya, 2016-10)
      Bachelor thesis
      Restricted access - author's decision
      Experimental implementation of a Quantum-Optical Coherence Tomography (Q-OCT) system, by means of measuring and quantifying induced coherence.
    • Narrowband photon pair source compatible with solid state quantum memories 

      Lago Rivera, Darío (Universitat Politècnica de Catalunya, 2016-09-08)
      Master thesis
      Open Access
      The generation of narrowband photon pairs compatible with solid state quantum memories is shown and analysed. This study is made in two different steps. In the beginning we implement a photon pair source with a periodically ...
    • New methodology for the Faraday rotation angle retrieval in the SMOS field of view 

      Rubino, Roselena; Duffo Ubeda, Núria; González Gambau, Verónica; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2018)
      Conference lecture
      Restricted access - publisher's policy
      In this work, a new methodology to estimate the Faraday Rotation Angle (FRA) from SMOS full-pol brightness temperature is presented. This approach is focused on retrieving the Vertical Total Electron Content (VTEC) and ...
    • Nonlocality in many-body quantum systems detected with two-body correlators 

      Tura, J.; Augusiak, Remigiusz; Sainz, A. B.; Lücke, B.; Klempt, C.; Lewenstein, Maciej; Acin, Antonio (Science Direct, 2015-07-30)
      Article
      Open Access
      Contemporary understanding of correlations in quantum many-body systems and in quantum phase transitions is based to a large extent on the recent intensive studies of entanglement in many-body systems. In contrast, much ...
    • Optical coherence tomography with a nonlinear interferometer 

      Sendra Molins, Lluc (Universitat Politècnica de Catalunya, 2018-07-17)
      Master thesis
      Open Access
      Covenantee:   Institut de Ciències Fotòniques (ICFO)
      We derive what is the signal and the sensitivity of a nonlinear interferometer (Mach-Zehnder or Michelson), that is a novel approach to perform Optical Coherence Tomography (OCT). The physical idea behind this goes back ...