  Quantum dot devices allow one to access the critical point of the two-channel
Kondo model. The effective critical theory involves a free Majorana fermion
quasiparticle localized on the dot. As a consequence, this critical point shows
both the phenomenon of non-Fermi liquid physics and fractionalization. Although
a violation of the Wiedemann-Franz law is considered a defining feature of
non-Fermi liquid systems, we show by exact calculations that it holds at the
critical point, providing a counterexample to this lore. Furthermore, we show
that the fractionalized Majorana character of the critical point can be
unambiguously detected from the heat conductivity, opening the door to a direct
experimental measurement of the elusive Majorana central charge
$c=\tfrac{1}{2}$.
