title: Taming the Dynamical Sign Problem in Real-Time Evolution of Quantum Many-Body Problems.
abstract: Current nonequilibrium Monte Carlo methods suffer from a dynamical sign problem that makes simulating real-time dynamics for long times exponentially hard. We propose a new "inchworm algorithm," based on iteratively reusing information obtained in previous steps to extend the propagation to longer times. The algorithm largely overcomes the dynamical sign problem, changing the scaling from exponential to quadratic. We use the method to solve the Anderson impurity model in the Kondo and mixed valence regimes, obtaining results both for quenches and for spin dynamics in the presence of an oscillatory magnetic field.
authors.affiliation: Department of Chemistry, Columbia University, New York, New York 10027, USA.|Department of Physics, Columbia University, New York, New York 10027, USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Cohen
authors.affiliation: Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Gull
authors.affiliation: Department of Chemistry, Columbia University, New York, New York 10027, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Reichman
authors.affiliation: Department of Physics, Columbia University, New York, New York 10027, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Millis