  Nambu Quantum Mechanics, proposed in Phys. Lett. B536, 305 (2002), is a
deformation of canonical Quantum Mechanics in which the manifold over which the
"phase" of an energy eigenstate time evolves is modified. This generalization
affects oscillation and interference phenomena through the introduction of two
deformation parameters that quantify the extent of deviation from canonical
Quantum Mechanics. In this paper, we constrain these parameters utilizing
atmospheric neutrino oscillation data, and $B^0$-$\overline{B^0}$ oscillation
data from Belle. Surprisingly, the bound from atmospheric neutrinos is stronger
than the bound from Belle. Various features of Nambu Quantum Mechanics are also
discussed.
