Regensburg 2000 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 17: Symposium: Der Quanten-Hall-Effekt wird 20 (II)
HL 17.4: Fachvortrag
Dienstag, 28. März 2000, 16:30–17:00, H15
Observation of Quasi-Particles with Fractional Charges — •M. Heiblum1, R. de Picciotto2, M. Reznikov3, T. G. Griffiths1, E. Comforti1, and V. Umansky1 — 1Braun Center for Submicron Research, Dept of Cond. Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel — 2Bell-Labs, Lucent Technologies, Murray Hill, NJ, 07974, US — 3Dept. of Condensed Matter Physics, Technion, Haifa, Israel
The fractional quantum Hall (FQH) effect, observed in the conduction properties of a high mobility 2DEG subjected to a strong perpendicular magnetic field, gives rise to current carrying fractionally charged quasi-particles. From this prediction in 1983 there were many attempts to verify the existence of such charges experimentally. Here we report the observation of quasi-particles with charge q=e/3 and e/5 detected, by shot noise measurements, when the so-called 1/3 and 2/5 channels are being weakly reflected by a quantum point contact, respectively. For fully transmitted channels there is no shot noise. These results demonstrate that electrons in these two channels are not interacting and flow independently. Moreover, it also shows that shot noise measures the actual charge of the current-carrying particle and is not directly related to the channel number (or conductance). Results will be also presented for strongly reflected edge states.