  High fidelity pressure measurements in the zero temperature limit provide a
unique opportunity to study the behavior of strongly interacting, itinerant
electrons with coupled spin and charge degrees of freedom. Approaching the
exactitude that has become the hallmark of experiments on classical critical
phenomena, we characterize the quantum critical behavior of the model,
elemental antiferromagnet chromium, lightly doped with vanadium. We resolve the
sharp doubling of the Hall coefficient at the quantum critical point and trace
the dominating effects of quantum fluctuations up to surprisingly high
temperatures.
