Now showing items 1-20 of 76

  • 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, 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
  • 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 ...
  • Exploring NbTiN superconducting single photon detectors with quantum detector tomography 

    Rivera Hernández, Juan Carlos (Universitat Politècnica de Catalunya, 2019-09-09)
    Master thesis
    Open Access
    The optical response of NbTiN superconducting single photon detectors is studied using quantum detector tomography which separates the detector response in single and multiple photon contributions. Three different NbTiN ...
  • Exploring nonlocal correlations in many-body systems 

    López Pastor, Víctor José (Universitat Politècnica de Catalunya, 2018-07-19)
    Master thesis
    Open Access
    We address the question of how to evaluate the Bell correlations depth, i.e. the number of parties sharing genuinely nonlocal correlations in a multipartite system. Previous work has shown that it is possible to construct ...