Experimental Evidence for Coulomb Charging Effects in an Open Quantum Dot at Zero Magnetic Field

C. -T. Liang, M. Y. Simmons, C. G. Smith, G. H. Kim, D. A. Ritchie, M. Pepper

Published 1998-09-25Version 1

We have measured the low-temperature transport properties of an open quantum dot formed in a clean one-dimensional channel. For the first time, at zero magnetic field, continuous and periodic oscillations superimposed upon ballistic conductance steps are observed when the conductance through the dot $G$ exceeds $2e^2/h$. We ascribe the observed conductance oscillations to evidence for Coulomb charging effects in an open dot. This is supported by the evolution of the oscillating features for $G>2e^2/h$ as a function of both temperature and barrier transparency. Our results strongly suggest that at zero magnetic field, current theoretical and experimental understanding of Coulomb charging effects overlooks charging in the presence of fully transmitted 1D channels.