  Electrically controllable quantum coherence in quantum dot clusters and
arrays based on graphene stripes with zigzag atomic edges (ZZ-stripes) is
studied using the Dirac equation and S-matrix technique. We find that
respective multiqubit circuits promise stable operation up to room temperatures
when the coherence time is prolonged up by a few orders of magnitude through
the intrinsic spectral narrowing owing to electron transport between at bands
in adjacent sections. Respectively, the coupling of qubits to a noisy
environment is diminished, while the inelastic electron-phonon scattering is
suppressed. The Stark splitting technique enables a broad range of operations
such as all{electrical tuning of the energy level positions and width, level
splitting, controlling of the inter-qubit coupling, and the coherence time. At
the resonant energies, the phase coherence spreads over thousands of periods.
Such phenomena potentially can be utilized in quantum computing and
communication applications at room temperature.
