OBSERVATION OF THE E 3 FRACTIONALLY CHARGED LAUGHLIN QUASI-PARTICLE/

The existence of fractional charges carrying current is experimentally demonstrated. Using a 2D electron system in a high perpendicular magn etic field we measure the shot noise associated with tunneling in the fractional quantum Hall regime at Landau level filling factor 1/3. The noise gives a direct determination of the quasiparticle charge, which is found to be e = e/3 as predicted by Laughlin. The existence of e/ 3 Laughlin quasiparticles is unambiguously confirmed by the shot noise to Johnson-Nyquist noise crossover found for temperature Theta = eV- ds/2k(B).