Browsing by Author "Martelo, L. M."

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    Superfluid weight and polarization amplitude in the one-dimensional bosonic Hubbard model
    (American Physical Society, 2019) Hetenyi, Balazs; Martelo, L. M.; Tanatar, Bilal
    We calculate the superfluid weight and the polarization amplitude for the one-dimensional bosonic Hubbard model with focus on the strong-coupling regime via variational, exact diagonalization, and strong coupling calculations. Our variational approach is based on the Baeriswyl wave function, implemented via Monte Carlo sampling. We derive the superfluid weight appropriately in a variational setting. We emphasize the importance of implementing the Peierls phase in position space and to allow for many-body interference effects, rather than implementing the Peierls phase as single particle momentum shifts. At integer filling, the Baeriswyl wave function gives zero superfluid response at any coupling. At half filling our variational superfluid weight is in reasonable agreement with exact diagonalization results. We also calculate the polarization amplitude, the variance of the total position, and the associated size scaling exponent, which corroborate that this variational approach produces an insulating state at integer filling. Our Baeriswyl based variational method is applicable to significantly larger system sizes than exact diagonalization or quantum Monte Carlo.
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    Variational Monte Carlo method for the Baeriswyl wave function: Application to the one-dimensional bosonic Hubbard model
    (American Physical Society, 2016) Hetényi, B.; Tanatar, Bilal; Martelo, L. M.
    A variational Monte Carlo method for bosonic lattice models is introduced. The method is based on the Baeriswyl projected wave function. The Baeriswyl wave function consists of a kinetic energy based projection applied to the wave function at infinite interaction, and is related to the shadow wave function already used in the study of continuous models of bosons. The wave function at infinite interaction, and the projector, are represented in coordinate space, leading to an expression for expectation values which can be evaluated via Monte Carlo sampling. We calculate the phase diagram and other properties of the bosonic Hubbard model. The calculated phase diagram is in excellent agreement with known quantum Monte Carlo results. We also analyze correlation functions.