# Quantum communication protocols by quantum walks with two coins. (arXiv:1802.02400v1 [quant-ph])

We introduce some new perfect state transfer and teleportation schemes by
quantum walks with two coins. Encoding the transferred information in coin 1
state and alternatively using two coin operators, we can perfectly recover the
information on coin 1 state at target position only by at most two times of
flipping operation. Based on quantum walks with two coins either on the line or
on the $N$-circle, we can perfectly transfer any qubit state. In addition,
using quantum walks with two coins either on complete graphs or regular graphs,
we can first implement perfect qudit state transfer by quantum walks. Compared
with existing schemes driven by one coin, more general graph structures can be
used to perfectly transfer more general state. Moreover, the external control
of coin operator during the transmitting process can be decreased greatly.
Selecting coin 1 as the sender and coin 2 as the receiver, we also study how to
realize generalized teleportation over long steps of walks by the above quantum
walk models. Because quantum walks is an universal quantum computation model,
our schemes may provide an universal platform for the design of quantum network
and quantum computer.