Nonequilibrium 1/f noise in rectifying nanopores.

We report a single rectifying conically shaped nanopore system with ion current fluctuations whose 1/f noise characteristics observed at low frequencies are voltage dependent. Switching the voltage polarity allows one to switch between a system that produces equilibrium and nonequilibrium 1/f ion current fluctuations. The nonequilibrium fluctuations in the high-conductance state of the device are characterized by exponential dependence of the normalized power spectrum on voltage. The asymmetric 1/f noise is found characteristic for rectifying polymer nanopores and absent in pores with Ohmic current-voltage curves.