Now showing items 1-20 of 81

    • A Combinatorial Approach to Nonlocality and Contextuality 

      Acin, Antonio; Fritz, Tobias; Leverrier, Anthony (Springer, 2015-03-01)
      Article
      Open Access
      So far, most of the literature on (quantum) contextuality and the Kochen– Specker theorem seems either to concern particular examples of contextuality, or be considered as quantum logic. Here, we develop a general formalism ...
    • A general framework for information-work interconvertibility in the quantum regime 

      Rodríguez Ramos, Constantino (Universitat Politècnica de Catalunya, 2016-09)
      Master thesis
      Open Access
      In this theoretical work we study three theorems that establish limitations to three basic processes in thermodynamics: an adiabatic process, an erasure process and a work extraction process. We propose a theoretical setting ...
    • Almost quantum correlations 

      Navascués, Miguel; Guryanova, Yelena; Hoban, Matty J.; Acín, Antonio (Nature Publishing group, 2015-02-20)
      Article
      Open Access
      Quantum theory is not only successfully tested in laboratories every day but also constitutes a robust theoretical framework: small variations usually lead to implausible consequences, such as faster-than-light communication. ...
    • An experimental setup for gray molasses sub-Doppler cooling of potassium gases 

      Bosch Aguilera, Manel (Universitat Politècnica de Catalunya, 2014-09-09)
      Master thesis
      Open Access
      [ÀNGLÈS] An experimental setup for cooling a gas of potassium atoms below the Doppler limit is presented. This method is known as gray molasses cooling. It will be implemented using light blue light blue detuned with respect ...
    • Applications of machine learning to studies of quantum phase transitions 

      Malo Roset, Laura (Universitat Politècnica de Catalunya, 2019-09-06)
      Master thesis
      Open Access
      In the past years Machine Learning has shown to be a useful tool in quantum many-body physics to detect phase transitions. Being able to identify phases via machine learning introduces the question of how did the algorithm ...
    • Bloch oscillations in optical and Zeeman lattices in the presence of spin-orbit coupling 

      Kartashov, Yaroslav V.; Konotop, Vladimir V; Zezyulin, Dmitry A; Torner Sabata, Lluís (2016-11-18)
      Article
      Open Access
      We address Bloch oscillations of a spin-orbit coupled atom in periodic potentials of two types: optical and Zeeman lattices. We show that in optical lattices the spin-orbit coupling allows controlling the direction of ...
    • Bose polarons at finite temperature and strong coupling 

      Guenther, Nils Eric; Massignan, Pietro Alberto; Lewenstein, Maciej; Bruun, Georg (2018-02-01)
      Article
      Open Access
      A mobile impurity coupled to a weakly interacting Bose gas, a Bose polaron, displays several interesting effects. While a single attractive quasiparticle is known to exist at zero temperature, we show here that the spectrum ...
    • Bound states in the continuum in anisotropic structures 

      Gomis Bresco, Jordi; Artigas García, David; Pujol Closa, Maria del Pilar; Torner Sabata, Lluís (Institute of Electrical and Electronics Engineers (IEEE), 2017)
      Conference report
      Restricted access - publisher's policy
      We report theoretical and experimental observation of radiationless bound states in the continuum (BIC) in waveguiding anisotropic structures. BICs may have all possible polarizations and be the only possible boundstates ...
    • Bound states in the continuum in spin-orbit-coupled atomic systems 

      Kartashov, Yaroslav V.; Konotop, Vladimir V; Torner Sabata, Lluís (2017-09-14)
      Article
      Restricted access - publisher's policy
      We show that the interplay between spin-orbit coupling and Zeeman splitting in atomic systems can lead to the existence of bound states in the continuum (BICs) supported by trapping potentials. Such states have energies ...
    • Can quantum effects due to a massless conformally coupled field avoid gravitational singularities? 

      Haro Cases, Jaume (2012-04)
      Article
      Restricted access - publisher's policy
      Using quantum corrections from massless fields conformally coupled to gravity, we study the possibility of avoiding singularities that appear in the flat Friedmann–Robertson–Walker model. We assume that the universe ...
    • Coherent control of a superconducting quantum bit 

      Luque Merino, Rafael (Universitat Politècnica de Catalunya, 2019-09-06)
      Master thesis
      Open Access
      Transmon qubits are at the forefront of solid state platforms for quantum computing. In this thesis, results obtained from the experimental study of a transmon qubit in a 3D cavity are presented. A complete view of the ...
    • Complexity Reduction in Large Quantum Systems: Fragment Identification and Population Analysis via a Local Optimized Minimal Basis 

      Mohr, Stephan; Masella, Michel; Ratcliff, Laura E.; Genovese, Luigi (American Chemical Society, 2017-07-21)
      Article
      Open Access
      We present, within Kohn–Sham density functional theory calculations, a quantitative method to identify and assess the partitioning of a large quantum-mechanical system into fragments. We then show how within this framework ...
    • Computación cuántica : nuevas perspectivas en el tratamiento de la información 

      Salas Peralta, Pedro J.; Sanz Sáenz, Ángel L. (Escola Tècnica Superior d'Enginyers de Telecomunicació de Barcelona, 2000)
      Article
      Open Access
    • Conformal data from finite entanglement scaling 

      Stojevic, Vid; Haegeman, Jutho; McCulloch, I. P.; Tagliacozzo, Luca; Verstraete, Frank (APS Physics, 2015-01-20)
      Article
      Open Access
      In this paper, we apply the formalism of translation invariant (continuous) matrix product states in the thermodynamic limit to (1 + 1)-dimensional critical models. Finite bond dimension bounds the entanglement entropy ...
    • Detection of nonlocality with two-body correlation functions 

      Aloy López, Albert (Universitat Politècnica de Catalunya, 2015-09-10)
      Master thesis
      Open Access
      Nonlocality detection in multipartite quantum systems is of great interest. The most popular tool to detect nonlocality in quantum systems are Bell inequalities. Most of the provided constructions of multipartite Bell ...
    • Dynamic structure factor of liquid He 4 across the normal-superfluid transition 

      Ferré Porta, Guillem; Boronat Medico, Jordi (2016-03-08)
      Article
      Open Access
      We have carried out a microscopic study of the dynamic structure factor of liquid He4 across the normal-superfluid transition temperature using the path integral Monte Carlo method. The ill-posed problem of the inverse ...
    • El Efecto túnel resonante de la magnetización a escala macroscópica abre las puertas de la computación cuántica 

      del Barco, E.; Hernández, J. M.; Ziolo, R. F.; Tejada, J. (Escola Tècnica Superior d'Enginyers de Telecomunicació de Barcelona, 1997)
      Article
      Open Access
    • Enhanced discretization of surface integral equations for resonant scattering analysis of sharp-edged plasmonic nanoparticles 

      Sekulic, Ivan; Tzarouchis, Dimitrios C.; Ylä-Oijala, Pasi; Úbeda Farré, Eduard; Rius Casals, Juan Manuel (American Physical Society (APS), 2019-04-10)
      Article
      Open Access
      The surface integral equation (SIE) method, discretized with the method of moments, is a well-established methodology for the scattering analysis of subwavelength plasmonic nanoparticles. SIEs are usually discretized with ...
    • Entanglement and non-locality of pure quantum states. 

      Sainz, Ana Belén (Universitat Politècnica de Catalunya, 2010-07-19)
      Master thesis
      Open Access
      We study the process of majorisation and interconversion of bipartite states, and apply the formalism for analysing the local and non-local content of pure bipartite entangled states. We proved that the states which are ...
    • Explorations of thermodynamics and information in quantum field theory 

      Teixidó Bonfill, Adam (Universitat Politècnica de Catalunya, 2020-05-20)
      Bachelor thesis
      Open Access
      Covenantee:   Institute for Quantum Computing (University of Waterloo) / University of Waterloo
      Podria dir-se que la termodinàmica ha sigut una de les rames més poderoses de la física, i la més universal per la seva varietat d'aplicacions. Des de motors de vapor fins a forats negres, les lleis de la termodinàmica ...