Now showing items 1-20 of 21

  • Diffusion Monte Carlo methods for spin-orbit-coupled ultracold Bose gases 

    Sánchez Baena, Juan; Boronat Medico, Jordi; Mazzanti Castrillejo, Fernando Pablo (American Physical Society (APS), 2018-11-27)
    Article
    Open Access
    We present two diffusion Monte Carlo (DMC) algorithms for systems of ultracold quantum gases featuring synthetic spin-orbit interactions. The first one is a spin-integrated DMC method which provides fixed-phase energy ...
  • Dipolar Bose Supersolid Stripes 

    Bombín Escudero, Raul; Boronat Medico, Jordi; Mazzanti Castrillejo, Fernando Pablo (2017-12-20)
    Article
    Open Access
    We study the superfluid properties of a system of fully polarized dipolar bosons moving in the XY plane. We focus on the general case where the polarization field forms an arbitrary angle a with respect to the Z axis, ...
  • Droplets of trapped quantum dipolar bosons 

    Macia Rey, Adrián; Sánchez Baena, Juan; Boronat Medico, Jordi; Mazzanti Castrillejo, Fernando Pablo (2016-11-10)
    Article
    Open Access
    Strongly interacting systems of dipolar bosons in three dimensions confined by harmonic traps are analyzed using the exact path integral ground-state Monte Carlo method. By adding a repulsive two-body potential, we find a ...
  • Ferromagnetic transition of a two-component Fermi gas of hard spheres 

    Arias de Saavedra, F.; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi; Polls, A. (2012-03-12)
    Article
    Open Access
    We use microscopic many-body theory to analyze the problem of itinerant ferromagnetism in a repulsive atomic Fermi gas of hard spheres. Using simple arguments we show that the available theoretical predictions for the onset ...
  • Few trapped quantum dipoles: quantum versus classical structures 

    Sánchez Baena, Juan; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi (2018-01-31)
    Article
    Open Access
    We analyze the ground state of a two-dimensional quantum system of a few strongly confined dipolar bosons. Dipoles arrange in different stable structures that depend on the tilting polarization angle and the anisotropy of ...
  • Gapped spectrum in pair-superfluid bosons 

    Astrakharchik, Grigori; Zillich, Robert E.; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi (2016-12-22)
    Article
    Open Access
    We study the ground state of a bilayer system of dipolar bosons with dipoles oriented by an external field perpendicularly to the two parallel planes. By decreasing the interlayer distance, for a fixed value of the strength ...
  • High-order time expansion path integral ground state 

    Rota, Riccardo; Casulleras Ambrós, Joaquín; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi (2010-01)
    Article
    Open Access
    The feasibility of path integral Monte Carlo ground state calculations with very few beads using a high-order short-time Green’s function expansion is discussed. An explicit expression of the evolution operator which provides ...
  • Low-dimensional weakly interacting Bose gases: nonuniversal equations of state 

    Astrakharchik, Grigori; Boronat Medico, Jordi; Kurbakov, I L; Lozovik, Y E; Mazzanti Castrillejo, Fernando Pablo (2010-01)
    Article
    Open Access
    The zero-temperature equation of state is analyzed in low-dimensional bosonic systems. We propose to use the concept of energy-dependent s-wave scattering length for obtaining estimations of nonuniversal terms in the energy ...
  • Microscopic description of anisotropic low-density dipolar Bose gases in two dimensions 

    Macia Rey, Adrián; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi; Zillich, R.E. (2011-09-19)
    Article
    Open Access
    A microscopic description of the zero-energy two-body ground state and many-body static properties of anisotropic homogeneous gases of bosonic dipoles in two dimensions at low densities is presented and discussed. By ...
  • Neighborhood-based stopping criterion for contrastive divergence 

    Romero Merino, Enrique; Mazzanti Castrillejo, Fernando Pablo; Delgado Pin, Jordi (2018-07)
    Article
    Open Access
    Restricted Boltzmann Machines (RBMs) are general unsupervised learning devices to ascertain generative models of data distributions. RBMs are often trained using the Contrastive Divergence (CD) learning algorithm, an ...
  • One-dimensional Bose gas in optical lattices of arbitrary strength 

    Astrakharchik, Grigori; Krutitsky, K.V.; Lewenstein, Maciej; Mazzanti Castrillejo, Fernando Pablo (2016-02-08)
    Article
    Open Access
    One-dimensional Bose gas with contact interaction in optical lattices at zero temperature is investigated by means of the exact diffusion Monte Carlo algorithm. The results obtained from the fundamental continuous model ...
  • Optical lattices as a tool to study defect-induced superfluidity 

    Astrakharchik, Grigori; Krutitsky, K.V.; Lewenstein, Maciej; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi (AMER PHYSICAL SOC, 2017-09-05)
    Article
    Open Access
    We study the superfluid response, the energetic and structural properties of a one-dimensional ultracold Bose gas in an optical lattice of arbitrary strength. We use the Bose-Fermi mapping in the limit of infinitely large ...
  • Phase diagram of dipolar bosons in two dimensions with tilted polarization 

    Macia Rey, Adrián; Boronat Medico, Jordi; Mazzanti Castrillejo, Fernando Pablo (2014-12-01)
    Article
    Open Access
    We analyze the ground state of a system of dipolar bosons moving in the XY plane and such that their dipolar moments are all aligned in a fixed direction in space. We focus on the general case where the polarization field ...
  • Quantum Monte Carlo estimation of complex-time correlations for the study of the ground-state dynamic structure function 

    Rota, R; Casulleras Ambrós, Joaquín; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi (2015-03-21)
    Article
    Open Access
    We present a method based on the path integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex ...
  • Self-bound Bose mixtures 

    Staudinger, Clemens; Mazzanti Castrillejo, Fernando Pablo; Zillich, Robert E. (American Physical Society (APS), 2018-08-31)
    Article
    Open Access
    Recent experiments confirmed that fluctuations beyond the mean-field approximation can lead to self-bound liquid droplets of ultradilute binary Bose mixtures. We proceed beyond the beyond-mean-field approximation and study ...
  • Single-particle versus pair superfluidity in a bilayer system of dipolar bosons 

    Macia Rey, Adrián; Astrakharchik, Grigori; Mazzanti Castrillejo, Fernando Pablo; Giorgini, Stefano; Boronat Medico, Jordi (2014-10-21)
    Article
    Open Access
    We consider the ground state of a bilayer system of dipolar bosons, where dipoles are oriented by an external field in the direction perpendicular to the parallel planes. Quantum Monte Carlo methods are used to calculate ...
  • Stopping criteria in contrastive divergence: Alternatives to the reconstruction error 

    Buchaca, David; Romero Merino, Enrique; Mazzanti Castrillejo, Fernando Pablo; Delgado Pin, Jordi (2014)
    Conference report
    Open Access
    Restricted Boltzmann Machines (RBMs) are general unsupervised learning devices to ascertain generative models of data distributions. RBMs are often trained using the Contrastive Divergence learning algorithm (CD), an ...
  • The effective two-particle interaction of cold atoms as derived from bragg scattering 

    Sarjonen, R.; Saarela, M.; Mazzanti Castrillejo, Fernando Pablo (2012-12)
    Article
    Open Access
    We study the dynamic structure function of ultracold alkali-metal gases for large scattering lengths and momenta where corrections to the mean field approximation become important. We compare our result with the Bragg-scattering ...
  • Two-dimensional mixture of dipolar fermions: Equation of state and magnetic phases 

    Comparin, Tommaso; Bombín Escudero, Raul; Holzmann, Markus; Mazzanti Castrillejo, Fernando Pablo; Boronat Medico, Jordi; Giorgini, Stefano (American Physical Society (APS), 2019-04-08)
    Article
    Open Access
    We study a two-component mixture of fermionic dipoles in two dimensions at zero temperature, interacting via a purely repulsive 1/r3 potential. This model can be realized with ultracold atoms or molecules when their dipole ...
  • Weighted contrastive divergence 

    Romero Merino, Enrique; Mazzanti Castrillejo, Fernando Pablo; Delgado Pin, Jordi; Buchaca Prats, David (2019-06)
    Article
    Restricted access - publisher's policy
    Learning algorithms for energy based Boltzmann architectures that rely on gradient descent are in general computationally prohibitive, typically due to the exponential number of terms involved in computing the partition ...