Particle number conservation in quantum many-body simulations with matrix productoperators

Abstract

Incorporating conservation laws explicitly into matrix product states (MPSs) has proven tomake numerical simulations of quantum many-body systems much less resource consuming.We will discuss here to what extent this concept can be used in simulation wherethe dynamically evolving entities are matrix product operators (MPOs). Quitecounter-intuitively the expectation of gaining in speed by sacrificing information about allbut a single symmetry sector is not in all cases fulfilled. It turns out that often theentanglement imposed by the global constraint of fixed particle number is the limitingfactor.