Mitigating the Sign Problem Through Basis Rotations

Understand

Quantum Monte Carlo simulations of quantum many body systems are plagued by the Fermion sign problem.

• The computational complexity of simulating Fermions scales exponentially in the projection time $\beta$ and system size.
• The sign problem is basis dependent and an improved basis, for fixed errors, lead to exponentially quicker simulations.
• We show how to use sign-free quantum Monte Carlo simulations to optimize over the choice of basis on large two-dimensional systems.