Electrochemically gated oligopeptide nanowires bridging gold electrodes: novel bio-nanoelectronic switches operating in aqueous electrolytic environments.

We present electronic structure and transport calculations that reveal that oligopeptide based molecular nanowires support unoccupied extended electronic states that span the length of the nanowire and are resistant to disorder. Electrochemical gating in aqueous electrolytes is shown to bring these extended states into resonance with the Fermi level of gold electrodes, transforming these nanowires from insulators into conductors. Thus oligopeptide nanowires are promising candidates for bionanoelectronic switches operating in the aqueous electrolytic environments native to biological systems.

The quantum interference effect transistor.

We give a detailed discussion of the quantum interference effect transistor (QuIET), a proposed device which exploits the interference between electron paths through aromatic molecules to modulate the current flow. In the off state, perfect destructive interference stemming from the molecular symmetry blocks the current, while in the on state, the current is allowed to flow by locally introducing either decoherence or elastic scattering. Details of a model calculation demonstrating the efficacy of the QuIET are presented, and various fabrication scenarios are proposed, including the possibility of using conducting polymers to connect the QuIET with multiple leads.

Controlling quantum transport through a single molecule.

We investigate multiterminal quantum transport through single monocyclic aromatic annulene molecules, and their derivatives, using the nonequilibrium Green function approach within the self-consistent Hartree-Fock approximation. We propose a new device concept, the quantum interference effect transistor, that exploits perfect destructive interference stemming from molecular symmetry and controls current flow by introducing decoherence and/or elastic scattering that break the symmetry. This approach overcomes the fundamental problems of power dissipation and environmental sensitivity that beset nanoscale device proposals.