Speaker
Simon Trebst
Description
Quantum Monte Carlo simulations of fermions are hampered
by the notorious sign problem whose most striking
manifestation is an exponential growth of sampling errors
with the number of particles. With the sign problem known to
be an NP-hard problem and any generic solution thus highly
elusive, the Monte Carlo sampling of interacting many-
fermion systems is commonly thought to be restricted to a
small class of model systems for which a sign-free basis has
been identified. Here we demonstrate that entanglement
measures, in particular the so-called Renyi entropies, can
intrinsically exhibit a certain robustness against the sign
problem in auxiliary-field quantum Monte Carlo approaches
and possibly allow for the identification of global ground-state
properties via their scaling behavior even in the presence of a
strong sign problem. We corroborate these findings via
numerical simulations of fermionic quantum phase transitions
of spinless fermions on the honeycomb lattice at and below
half-filling.
