Deconfined quantum critical point in the extended Hubbard model: a sign-problem-free quantum Monte Carlo study

Deconfined quantum critical point (DQCP) describes a type of quantum phase transitions at T=0 beyond Landau paradigm, where a continuous transition appears between ordered phases with incompatible broken symmetries. Convincing evidences of DQCP in correlated fermionic systems are scarce. Here we study the quantum phase diagram and phase transition on an extended Hubbard model of fermions on the square lattice. By performing determinant quantum Monte Carlo simulation, we establish the ground-state phase diagram of this model, and more intriguingly, show convincing evidence of a continuous phase transition between valence-bond-solid (VBS) and antiferromagnetic (AF) phases when the interaction strength is varied. We believe that our study provides a novel platform for the investigation of DQCP in the strongly correlated fermionic systems.