  Quantum walks have gained significant attention over the past decades, mainly
because of their variety of implementations and applications. Atomic quantum
walks are typically subject to spontaneous emissions arising from the control
fields. We investigate spontaneous emission in an atom optics kicked rotor
quantum walk. Here, spontaneous emission occurs naturally due to the driving by
the kicks, and it is generally viewed as a nuisance in the experiment. We find,
however, that spontaneous emission may induce asymmetries in an otherwise
symmetric quantum walk. Our results underscore the utility of spontaneous
emission and the application of the asymmetric evolution in the walker's space,
i.e. for the construction of a quantum walk ratchet or for Parrondo-like
quantum games. This highlights the potential for reinterpreting seemingly
adverse effects as beneficial under certain conditions, thus broadening the
scope of quantum walks and their applications.
