  We present the experimental realization of a scheme, based on single-photon
interference, for implementing superpositions of distinct quantum operations.
Its application to a thermal light field (a well-categorized classical entity)
illustrates quantum superposition from a new standpoint and provides a direct
and quantitative verification of the bosonic commutation relation between
creation and annihilation operators. By shifting the focus towards operator
superpositions, this result opens interesting alternative perspectives for
manipulating quantum states.

Quantum Physics