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Direct Observation of Macroscopic Charge Quantization



P Lafarge, H Pothier, Edwin R. Williams, D Esteve, C Urbina, Michel H. Devoret


The circuit formed by a nanoscale tunnel junction in series with a capacitance and a voltage source is the building block of most multi-junction circuits of single electronics. The state of this single electron box is entirely determined by the number n of extra electrons on the intermediate island electrode between the junction and the capacitance. We have fabricated such a system and measured the charge on the junction capacitance, which is directly related to the average value of n, as a function of the bias voltage using a Fulton-Dolan electrometer. At low temperature, the junction charge followed by e-periodic sawtooth function expected from the theory of macroscopic charge quantization. Strikingly, e-periodic variations were also observed when the box was superconducting. The thermal rounding of the sawtooth function is well explained by a simple model, except at the lowest temperatures.
Journal of Physics B-Atomic Molecular and Optical Physics


charge quantization, Coulomb blockade, single electron tunneling


Lafarge, P. , Pothier, H. , Williams, E. , Esteve, D. , Urbina, C. and Devoret, M. (1991), Direct Observation of Macroscopic Charge Quantization, Journal of Physics B-Atomic Molecular and Optical Physics (Accessed April 20, 2024)
Created November 30, 1991, Updated October 12, 2021