  The relevance of magnetic impurity problems in cold atom systems depends
crucially on the nature of exchange interaction between itinerant fermionic
atoms and a localized impurity atom. In particular, Kondo physics occurs only
if the exchange interaction is anti-ferromagnetic, and strong enough to yield
high enough Kondo temperature ($T_K/T_F \ge 0.1$). Focusing, as an example, on
the experimentally accessible system of ultra-cold $^{173}$Yb atoms, it is
shown that the sign and strength of an exchange interaction between an
itinerant Yb($^{1}$S$_{0}$) atom and a trapped Yb($^{3}$P$_{0}$) atom can be
optically controlled. Explicitly, as the light intensity increases (from zero),
the exchange interaction changes from ferromagnetic to anti-ferromagnetic. When
the light intensity is just below a singlet Feshbach resonance, the singlet
scattering length $a_S$ is large and negative, and the Kondo temperature
increases sharply.
