Duplex quantum communication through a spin chain

Data multiplexing within a quantum computer can allow for the simultaneous transfer of multiple streams of information over a shared medium thereby minimizing the number of channels needed for requisite data transmission. Here, we investigate a two-way quantum communication protocol using a spin chain placed in an external magnetic field. In our scheme, Alice and Bob each play the role of a sender and a receiver as two states, cos(({theta}{sub 1}/2))0+sin(({theta}{sub 1}/2))e{sup i{phi}{sub 1}}1 and cos(({theta}{sub 2}/2))0+sin(({theta}{sub 2}/2))e{sup i{phi}{sub 2}}1, are transferred through one channel simultaneously. We find that the transmission fidelity at each end of a spin chain can usually be enhanced by the presence of a second party. This is an important result for establishing the viability of duplex quantum communication through spin chain networks.