Publication : t19/118

A Quantum Monte Carlo algorithm for out-of-equilibrium Green's functions at long times

Bertrand C. ()
Parcollet O. (CEA, IPhT (Institut de Physique Théorique), F-91191 Gif-sur-Yvette, France)
Maillard A. ()
Waintal X. ()
Abstract:
We present a quantum Monte-Carlo algorithm for computing the perturbative expansion in power of the coupling constant U of the out-of-equilibrium Green's functions of interacting Hamiltonians of fermions. The algorithm extends the one presented in Phys. Rev. B 91 245154 (2015), and inherits its main property: it can reach the infinite time (steady state) limit since the computational cost to compute order Un is uniform versus time; the computing time increases as 2n. The algorithm is based on the Schwinger-Keldysh formalism and can be used for both equilibrium and out-of-equilibrium calculations. It is stable at both small and long real times including in the stationary regime, because of its automatic cancellation of the disconnected Feynman diagrams. We apply this technique to the Anderson quantum impurity model in the quantum dot geometry to obtain the Green's function and self-energy expansion up to order U10 at very low temperature. We benchmark our results at weak and intermediate coupling with high precision Numerical Renormalization Group (NRG) computations as well as analytical results
Année de publication : 2019
Revue : Phys. Rev. B 100 125129 (2019)
Preprint : arXiv:1903.11636
Keywords : Condensed Matter - Strongly Correlated Electrons
Langue : Anglais
NB : Bibcode : 2019arXiv190311636B

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