  The challenge of building a scalable quantum processor requires consolidation
of the conflicting requirements of achieving coherent control and preservation
of quantum coherence in a large scale quantum system. Moreover, the system
should be compatible with miniaturization and integration of quantum circuits.
Mesoscopic solid state systems such as superconducting islands and quantum dots
feature robust control techniques using local electrical signals and
self-evident scaling based on advances in fabrication; however, in general the
quantum states of solid state devices tend to decohere rapidly. In contrast,
quantum optical systems based on trapped ions and neutral atoms exhibit
dramatically better coherence properties, while miniaturization of atomic and
molecular systems, and their integration with mesoscopic electrical circuits,
remains an important challenge. Below we describe methods for the integration
of a single particle system -- an isolated polar molecule -- with mesoscopic
solid state devices in a way that produces robust, coherent, quantum-level
control. The methods described include the trapping, cooling, detection,
coherent manipulation and quantum coupling of isolated polar molecules at
sub-micron dimensions near cryogenic stripline microwave resonators. We show
that electrostatically trapped polar molecules can exhibit strong confinement
and fast, purely electrical gate control. Furthermore, the effect of electrical
noise sources, a key issue in quantum information processing, can be suppressed
to very low levels via appropriate preparation and manipulation of the polar
molecules. Our setup provides a scalable cavity QED-type quantum computer
architecture, where entanglement of distant qubits stored in long-lived
rotational molecular states is achieved via exchange of microwave photons.
