  Quantum mechanics allows coherent superposition between different states of
matter. This quality is responsible for major non-classical phenomena that
occur in quantum systems. Beyond states, coherent superpositions are also
possible between quantum evolutions. We characterize such superpositions here.
A resource theoretic framework is developed to quantify superposition present
in an arbitrary quantum evolution. In addition to characterization, the
framework considers superposition as a quantum resource. This resource can be
exploited to perform certain quantum tasks that are otherwise impossible. We
identify maximally resourceful evolutions and demonstrate how these could
enable one to implement arbitrary quantum operations and super-operations. We
also discuss the roles of superposition to exhibit non-classical behaviors
present in evolutions, for example, a-causality, temporal Bell correlations,
and indefinite temporal and causal orders.
