  Measurement-device-independent quantum key distribution (MDI-QKD) provides us
a powerful approach to resist all attacks at detection side. Besides the
unconditional security, people also seek for high key generation rate, but
MDI-QKD has relatively low key generation rate. In this paper, we provide an
efficient approach to increase the key generation rate of MDI-QKD by adopting
multiple degrees of freedom (DOFs) of single photons to generate keys. Compared
with other high-dimension MDI-QKD protocols encoding in one DOF, our protocol
is more flexible, for our protocol generating keys in independent subsystems
and the detection failure or error in a DOF not affecting the information
encoding in other DOFs. Based on above features, our MDI-QKD protocol may have
potential application in future quantum communication field.
