  We study a charge two-channel Kondo model, demonstrating that recent
experiments [Iftikhar et al, Nature 526, 233 (2015)] realize an essentially
perfect quantum simulation -- not just of its universal physics, but also
nonuniversal effects away from the scaling limit. Numerical renormalization
group (NRG) calculations yield conductance lineshapes encoding RG flow to a
critical point involving a free Majorana fermion. By mimicking the experimental
protocol, the experimental curve is reproduced quantitatively over 9 orders of
magnitude, although we show that far greater bandwidth/temperature separation
is required to obtain the universal result. Fermi liquid instabilities are also
studied: In particular, our exact analytic results for non-linear conductance
provide predictions away from thermal equilibrium, in the regime of existing
experiments.
