Linear Ensemble-Constrained Quantum Monte Carlo: From Dilute Fermi Gas to Flat-Band Ferromagnetism
The Linear Ensemble-Constrained Quantum Monte Carlo (LEC-QMC) algorithm uses a stabilized QR update to achieve linear computational scaling, allowing unbiased simulations of strongly correlated low-density phases. It successfully confirmed ferromagnetic ground states in flat-band systems by explicitly enforcing particle number constraints, providing a rigorous tool for studying emergent phenomena in dilute quantum matter.