  Structured photons are nowadays an interesting resource in classical and
quantum optics due to the richness of properties they show under propagation,
focusing and in their interaction with matter. Vectorial modes of light in
particular, a class of modes where the polarization varies across the beam
profile, have already been used in several areas ranging from microscopy to
quantum information. One of the key ingredients needed to exploit the full
potential of complex light in quantum domain is the control of quantum
interference, a crucial resource in fields like quantum communication, sensing
and metrology. Here we report a tunable photon-photon interference between
vectorial modes of light. We demonstrate how a properly designed spin-orbit
device can be used to control quantum interference between vectorial modes of
light by simply adjusting the device parameters and no need of interferometric
setups. We believe our result can find applications in fundamental research and
quantum technologies based on structured light by providing a new tool to
control quantum interference in a compact, efficient and robust way.
