QuSpin: a Python Package for Dynamics and Exact Diagonalisation of Quantum Many Body Systems. Part II: bosons, fermions and higher spins

TL;DR

QuSpin is an enhanced Python package enabling exact diagonalization and quantum dynamics simulations of bosons, fermions, and spins, supporting complex symmetries and various models for research and education.

Contribution

This update introduces new features for simulating diverse quantum many-body systems with symmetry considerations and time evolution, demonstrated through seven detailed examples.

Findings

Supports a wide range of models including Ising, SSH, Fermi-Hubbard, Bose-Hubbard, and mixtures.

Enables (imaginary) time evolution and symmetry use in higher dimensions.

Provides a user-friendly interface with comprehensive documentation.

Abstract

We present a major update to QuSpin, SciPostPhys.2.1.003 -- an open-source Python package for exact diagonalization and quantum dynamics of arbitrary boson, fermion and spin many-body systems, supporting the use of various (user-defined) symmetries in one and higher dimension and (imaginary) time evolution following a user-specified driving protocol. We explain how to use the new features of QuSpin using seven detailed examples of various complexity: (i) the transverse-field Ising chain and the Jordan-Wigner transformation, (ii) free particle systems: the Su-Schrieffer-Heeger (SSH) model, (iii) the many-body localized 1D Fermi-Hubbard model, (iv) the Bose-Hubbard model in a ladder geometry, (v) nonlinear (imaginary) time evolution and the Gross-Pitaevskii equation on a 1D lattice, (vi) integrability breaking and thermalizing dynamics in the translationally-invariant 2D transverse-field Ising model, and (vii) out-of-equilibrium Bose-Fermi mixtures. This easily accessible and user-friendly package can serve various purposes, including educational and cutting-edge experimental and theoretical research. The complete package documentation is available under http://weinbe58.github.io/QuSpin/index.html.