  Orbital angular momentum of light has recently been recognized as a new
degree of freedom to encode information in quantum communication using light
pulses. Methods to extract this information include reversing the process by
which such twisted light was created in the first place or interference with
other beams. Here, we propose an alternative new way to directly read out the
extra information encoded in twisted light using plasmonic nanoantennas by con-
verting the information about the orbital angular momentum of light into
spectral information using bright and dark modes. Exemplarily considering
rotation-symmetrical nanorod nanoan- tennas we show that their scattering
cross-section is sensitive to the value of the orbital angular momentum
combined with the polarisation of an incident twisted light beam. Explaining
the twist-dependence of the excited modes with a new analytical model our
results pave the way to twisted light nanoplasmonics, which is of central
importance for future on-chip communication using orbital angular momentum of
light.
