arXiv:1106.3502 · Physical Review A
Duplex quantum communication through a spin chain
Zhao-Ming Wang, C. Allen Bishop, Yongjian Gu, Bin Shao
Abstract
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, $\mathrm{cos}(\frac{{\ensuremath{\theta}}_{1}}{2})\left|0\right\ensuremath{\rangle}+\mathrm{sin}(\frac{{\ensuremath{\theta}}_{1}}{2}){e}^{i{\ensuremath{\varphi}}_{1}}\left|1\right\ensuremath{\rangle}$ and $\mathrm{cos}(\frac{{\ensuremath{\theta}}_{2}}{2})\left|0\right\ensuremath{\rangle}+\mathrm{sin}(\frac{{\ensuremath{\theta}}_{2}}{2}){e}^{i{\ensuremath{\varphi}}_{2}}\left|1\right\ensuremath{\rangle}$, 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.