arXiv subjects

Giuseppe Carleo

Publications and source records attributed to Giuseppe Carleo.

112 records · Page 7Linked to original sources

arXiv2010

Reptation quantum Monte Carlo for lattice Hamiltonians with a directed-update scheme

We provide an extension to lattice systems of the reptation quantum Monte Carlo algorithm, originally devised for continuous Hamiltonians. For systems affected by the sign problem, a method to systematically improve upon the so-called fixed-node approximation is also proposed. The generality of the method, which also takes advantage of a canonical worm algorithm scheme to measure off-diagonal observables, makes it applicable to a vast variety of quantum systems and eases the study of their ground-state and excited-states properties. As a case study, we investigate the quantum dynamics of the one-dimensional Heisenberg model and we provide accurate estimates of the ground-state energy of the two-dimensional fermionic Hubbard model.

cond-mat.other↗

arXiv2010

The itinerant ferromagnetic phase of the Hubbard model

Using a newly developed quantum Monte Carlo technique, we provide strong evidence for the stability of a saturated ferromagnetic phase in the high-density regime of the two-dimensional infinite-U Hubbard model. By decreasing the electron density, a discontinuous transition to a paramagnetic phase is observed, accompanied by a divergence of the susceptibility on the paramagnetic side. This behavior, resulting from a high degeneracy among different spin sectors, is consistent with an infinite-order phase transition. The remarkable stability of itinerant ferromagnetism renews the hope to describe this phenomenon within a purely kinetic mechanism and will facilitate the validation of experimental quantum simulators with cold atoms loaded in optical lattices.

cond-mat.str-el↗

arXiv2009

Bose-Einstein condensation in quantum glasses

The role of geometrical frustration in strongly interacting bosonic systems is studied with a combined numerical and analytical approach. We demonstrate the existence of a novel quantum phase featuring both Bose-Einstein condensation and spin-glass behaviour. The differences between such a phase and the otherwise insulating "Bose glasses" are elucidated.

cond-mat.dis-nn↗

arXiv2009

Zero-temperature dynamics of solid 4He from quantum Monte Carlo simulations

The lattice dynamics of hcp crystalline 4He is studied at zero temperature and for two different densities (near and far from melting), using a ground-state path-integral quantum Monte Carlo technique. The complete phonon dispersion is obtained, with particular attention to the separation of optic and acoustic branches and to the identification of transverse modes. Our study also sheds light onto the residual coherence affecting quasiparticle excitations in the intermediate momentum region, in-between the phonon and nearly-free particle regimes.

cond-mat.other↗