Field moment expansion method for interacting Bosonic systems

Abstract

We introduce a numerical method and python package, https://github.com/andillio/CHiMES, that simulates quantum systems initially well approximated by mean field theory using a second order extension of the classical field approach. We call this the field moment expansion method. In this way, we can accurately approximate the evolution of first and second field moments beyond where the mean field theory breaks down. This allows us to estimate the quantum breaktime of a classical approximation without any calculations external to the theory. We investigate the accuracy of the field moment expansion using a number of well studied quantum test problems. Interacting Bosonic systems similar to scalar field dark matter are chosen as test problems. We find that successful application of this method depends on two conditions: the quantum system must initially be well described by the classical theory, and that the growth of the higher order moments be hierarchical.

Accepted to Phys. Rev. D

References in corpus (4)

• The multi-configurational time-dependent Hartree method for bosons: Many-body dynamics of bosonic systems
• First star-forming structures in fuzzy cosmic filaments
• Quantum and Classical Behavior in Interacting Bosonic Systems
• Density perturbations in axion-like particles: classical vs quantum field treatment