Figure 1: Schematic phase diagram with two very different spin configurations. At the deconfined quantum critical point $g_{\text{c}}$, the Néel order parameter $O_1$ and the valence bond crystal order parameter $O_2$ vanish continuously from the two sides and spin-$1/2$ excitations (shown in inset as a free spin in a sea of singlet pairs) become deconfined. At this point, free spinons and photons emerge as dynamical variables in the system.