Experimental realization of a primary-filling e/3 quasiparticle interferometer

We report experiments on a Laughlin quasiparticle interferometer where the entire system is on the 1/3 primary fractional quantum Hall plateau. Electron-beam lithography is used to define an approximately circular 2D electron island separated from the 2D bulk by two wide constrictions. The interferometer consists of counterpropagating chiral edge channels coupled by quantum-coherent tunneling in the two constrictions, thus enclosing an island area. Interference fringes are observed as conductance oscillations, similar to the Aharonov-Bohm effect. The flux and charge periods of the interferometer device are calibrated with electrons in the integer quantum Hall regime. In the fractional regime we observe magnetic flux and charge periods h/e and e/3, respectively, corresponding to creation of one quasielectron in the island. Quantum theory predicts a 3h/e flux period for charge e/3, integer statistics particles. Accordingly, the observed periods demonstrate the anyonic statistics of Laughlin quasiparticles.