Title: Tunable Quantum Criticality and Super-ballistic Transport in a `Charge' Kondo Circuit,
Abstract: Quantum phase transitions are ubiquitous in many exotic behaviors of
strongly-correlated materials. However the microscopic complexity impedes their
quantitative understanding. Here, we observe thoroughly and comprehend the rich
strongly-correlated physics in two profoundly dissimilar regimes of quantum
criticality. With a circuit implementing a quantum simulator for the
three-channel Kondo model, we reveal the universal scalings toward different
low-temperature fixed points and along the multiple crossovers from quantum
criticality. Notably, an unanticipated violation of the maximum conductance for
ballistic free electrons is uncovered. The present charge pseudospin
implementation of a Kondo impurity opens access to a broad variety of
strongly-correlated phenomena.