  The theory of deconfined quantum critical points describes phase transitions
at temperature T = 0 outside the standard paradigm, predicting continuous
transformations between certain ordered states where conventional theory
requires discontinuities. Numerous computer simulations have offered no proof
of such transitions, however, instead finding deviations from expected scaling
relations that were neither predicted by the DQC theory nor conform to standard
scenarios. Here we show that this enigma can be resolved by introducing a
critical scaling form with two divergent length scales. Simulations of a
quantum magnet with antiferromagnetic and dimerized ground states confirm the
form, proving a continuous transition with deconfined excitations and also
explaining anomalous scaling at T > 0. Our findings revise prevailing paradigms
for quantum criticality, with potentially far-reaching implications for many
strongly-correlated materials.
