  We explore the potential application of graphene-based qubits in photonic
quantum communications. In particular, the valley pair qubit in double quantum
dots of gapped graphene is investigated as a quantum memory in the
implementation of quantum repeaters. For the application envisioned here, our
work extends the recent study of the qubit (Wu et al., arXiv: 1104.0443; Phys.
Rev. B 84, 195463 (2011)) to the case where the qubit is placed in a normal
magnetic field-free configuration. It develops, for the configuration, a method
of qubit manipulation, based on a unique AC electric field-induced,
valley-orbit interaction-derived mechanism in gapped graphene. It also studies
the optical response of graphene quantum dots in the configuration, in terms of
valley excitation with respect to photonic polarization, and illustrates
faithful photon \leftrightarrow valley quantum state transfers. This work
suggests the interesting prospect of an all-graphene approach for the solid
state components of a quantum network, e.g., quantum computers and quantum
memories in communications.
