S. M. Cronenwett, Department of Applied Physics and DIMES, Delft University of Technology, Post Office Box 5046, 2600 GA Delft, Netherlands, and Department of Physics, Stanford University, Stanford, CA, 94305–4060, USA. T. H. Oosterkamp and L. P. Kouwenhoven, Department of Applied Physics and DIMES, Delft University of Technology, Post Office Box 5046, 2600 GA Delft, Netherlands. (At 1998-07-24)
