Cs encapsulation and interacting noise sources in carbon nanotubes

We study the effect of Cs encapsulation on the transport and noise properties of carbon nanotubes, and report very large two-level current fluctuations observed in the time-traces of the current at low temperatures. When several two-level fluctuations are active at the same time, we find they are interacting each other. Observed noise behaviors are attributed to the movable cluster of Cs ions encapsulated in the carbon nanotube.