  We study theoretically the feasibility of using transverse electronic
transport within a nanopore for rapid DNA sequencing. Specifically, we examine
the effects of the environment and detection probes on the distinguishability
of the DNA bases. We find that the intrinsic measurement bandwidth of the
electrodes helps the detection of single bases by averaging over the current
distributions of each base. We also find that although the overall magnitude of
the current may change dramatically with different detection conditions, the
intrinsic distinguishability of the bases is not significantly affected by pore
size and transverse field strength. The latter is the result of very effective
stabilization of the DNA by the transverse field induced by the probes, so long
as that field is much larger than the field that drives DNA through the pore.
In addition, the ions and water together effectively screen the charge on the
nucleotides, so that the electron states participating in the transport
properties of the latter ones resemble those of the uncharged species. Finally,
water in the environment has negligible direct influence on the transverse
electrical current.
