2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/135102Using ground-state projector quantum Monte Carlo simulations in the valence bond basis, it is demonstrated that non-frustrating four-spin interactions can destroy the Neel order of the two-dimensional S=1/2 Heisenberg antiferromagnet and drive it into a valence-bond solid (VBS) phase. Results for spin and dimer correlations are consistent with a single continuous transition, and all data exhibit finite-size scaling with a single set of exponents; z=1, nu=0.78 +/- 0.03, and eta=0.26 +/- 0.03. The unusually large eta and an emergent U(1) symmetry, detected using VBS order parameter histograms, provide strong evidence for a deconfined quantum critical point.4 pages, 5 figures. v2: typo in Fig. 2 corrected. v3: minor changes, published versionStrongly Correlated ElectronsSuperconductivitytext