Observation of Coulomb Blockade and Interference Using a Carbon Nanotube Tip

Abstract

Using a carbon nanotube (CNT) bundle tip as a field emitter, we have observed both Coulomb blockade and interference fringes in consecutive measurements. When Coulomb blockade is observed, decoherence of the electron wave occurs. This was observed using a double-tunnel junction consisting of a CNT tip and a CNT sample. When the CNT sample was projected onto a screen by an electron wave from the CNT tip, interference fringes were observed. This shows that the electron is first observed at the central electrode as a Coulomb blockade, next it is observed at the CNT sample as current when the electron leaves from the central electrode (the CNT tip) and finally observed as fringes passing through the CNT sample. These results show that the system's wave function cannot be written as a direct product of independent substates.