  Mechanical oscillators which respond to radiation pressure are a promising
means of transferring quantum information between light and matter.
Optical--mechanical state swaps are a key operation in this setting. Existing
proposals for optomechanical state swap interfaces are only effective in the
resolved sideband limit. Here, we show that it is possible to fully and
deterministically exchange mechanical and optical states outside of this limit,
in the common case that the cavity linewidth is larger than the mechanical
resonance frequency. This high-bandwidth interface opens up a significantly
larger region of optomechanical parameter space, allowing generation of
non-classical motional states of high-quality, low-frequency mechanical
oscillators.
