  We investigate a quantum dot (Anderson impurity) coupled to metallic leads,
with a time-periodic voltage bias across the device. Using a time-dependent
Schrieffer-Wolff transformation, we show that the Floquet Hamiltonian of the
model can be mapped onto a two-channel Kondo model, in which the impurity is
screened by separate conduction bands corresponding to parity-even and odd
superpositions of the metallic leads. By changing the frequency and amplitude
of the perturbation, one can tune the system to a quantum critical point with
symmetric coupling of the impurity to both channels. For the understanding of
the driven state, energy absorption from the drive must be considered: Although
the absorption at the impurity is balanced by the energy flow into the
conduction band, locally it leads to non-thermal distribution functions which
can have a detrimental effect on the Kondo physics. However, a numerical
simulation demonstrates that the absorption can be systematically suppressed at
a fixed value of the induced couplings by increasing the frequency, so that the
time-averaged dynamics in the driven one-channel Anderson model can be used to
study the critical behavior of the two-channel model.
