  The possibility for quantum and classical communication to coexist on the
same fibre is important for deployment and widespread adoption of quantum key
distribution (QKD) and, more generally, a future quantum internet. While
coexistence has been demonstrated for different QKD implementations, a
comprehensive investigation for measurement-device independent (MDI) QKD -- a
recently proposed QKD protocol that cannot be broken by quantum hacking that
targets vulnerabilities of single-photon detectors -- is still missing. Here we
experimentally demonstrate that MDI-QKD can operate simultaneously with at
least five 10 Gbps bidirectional classical communication channels operating at
around 1550 nm wavelength and over 40 km of spooled fibre, and we project
communication rates in excess of 10 THz when moving the quantum channel from
the third to the second telecommunication window. The similarity of MDI-QKD
with quantum repeaters suggests that classical and generalised quantum networks
can co-exist on the same fibre infrastructure.
