Now showing items 1-20 of 86

    • 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 ...
    • Ag2ZnSnS4–ZnS core–shell colloidal quantum dots: a near-infrared luminescent material based on environmentally friendly elements 

      Saha, Avijit; Konstantatos, Gerasimos (RSC, 2021-05-07)
      Article
      Open Access
      Low cost, multinary colloidal quantum dots (QDs) based on environmentally friendly elements, with bright, narrow-width, tunable near-infrared (NIR) luminescence are promising alternatives to Cd and Pb chalcogenide QDs for ...
    • 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 ...
    • 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 ...
    • 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 ...
    • Development of hole selective contacts on p-type c-Ge substrates 

      Lladós Cos, Òscar (Universitat Politècnica de Catalunya, 2020-12)
      Master thesis
      Open Access
      Thermophotovoltaic devices convert heat to electricity by absorbing infra-red photons with low energies. In order to do so semiconductors materials with low band-gap are needed. The crystalline Germanium (cGe) is an ...
    • 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 ...
    • 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
      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 ...
    • 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 ...
    • External fluctuations in front propagation 

      Armero Rovira, J.; Sancho, Jose Maria; Casademunt, Jaume; Lacasta Palacio, Ana María; Ramírez de la Piscina Millán, Laureano; Sagués Mestre, Francesc (American Physical Society, 1996-04-01)
      Article
      Open Access
      We study the effects of external noise in a one-dimensional model of front propagation. Noise is introduced through the fluctuations of a control parameter leading to a multiplicative stochastic partial differential equation. ...
    • First-passage times for a marginal state driven by colored noise 

      Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (The American Physical Society, 1991-01-18)
      Article
      Open Access
      The dynamical process through a marginal state (saddle point) driven by colored noise is studied. For small correlation time of the noise, the mean first-passage time and its variance are calculated using standard methods. ...