Bunching of fractionally charged quasiparticles tunnelling through high-potential barriers

Abstract

Shot noise measurements were recently exploited to measure the charge of the quasiparticles in the Fractional Quantum Hall (FQH) regime. For fractional filling factors ν = 1/3 and 2/5 of the first Landau level, fractional charges q = e/3 and e/5, respectively, were measured [1][2][3]. We investigate here the interaction of e/3 quasiparticles with a strong backscatterer and find unexpected results.When a weak backscatterer is introduced in the path of an otherwise noiseless current of quasiparticles, stochastic partitioning of the quasiparticles takes place and shot noise proportional to their charge appears. Specifically, at ν = 1/3, noise corresponding to q = e/3 appears. However, the measured charge increases monotonically as backscattering becomes stronger, approaching asymptotically q = e [4,5]. In other words, only electrons, or alternatively, three bunched quasiparticles, tunnel through high potential barriers when impinged by a noiseless current of quasiparticles. Here we show that such bunching of quasiparticles by a strong backscatterer depends on the average occupation (dilution) of the impinging quasiparticle current. For a very dilute impinging current, bunching ceases altogether and the transferred charge approaches q = e/3.

Fluctuation-dissipation theorem for chiral systems in nonequilibrium steady states

“…13). For example, it cannot explain observed quasiparticle transmission through an opaque barrier without bunching into electrons 14,15 . Thus, it is important to test major assumptions of CLL.…”

Antidot tunneling between quantum Hall liquids with different filling factors

“…In the simplest case of FQHL with the filling factor ν = 1/odd, the quasiparticles that tunnel through the liquid between its edges coincide with the quasiparticles in the bulk [3] and their fractional charge νe can be measured experimentally [4,5]. So far, fractional statistics of quasiparticle has not been directly observed in experiments, although there is experimental [6] and theoretical [7] interest to manifestations of this statistics in the noise correlators of the tunnel currents.Strong tunneling between edges of FQHLs with different filling factors should create quasiparticles which are different from those in the bulk of the liquids but still have fractional charge and statistics [8,9]. Untill now, such tunneling has been considered only in the geometry of a single point contact [8] or multiple contacts [9] for which the interference between different contacts is not important (i.e., the edges do not form closed loops).…”

“…were the Kronecker symbol δ ij is defined modulo m. These relations originate from the effective flux through the antidot which includes external magnetic flux and statistical contribution and is equal to n = n 1 − n 2 (in units of Φ 0 ) in the strong-tunneling limit (6). Because of the interference in the two point contacts, tunneling amplitudes of quasiparticles of charge 1/m acquire the phases e ±i2πn/m which distinguish m states of the antidot with different fluxes n ′ = n mod(m).…”

Nonequilibrium plasmons and transport properties of a double-junction quantum wire

“…For instance, the shot noise of the edge states was used to measure the factional charge ge of the quasiparticles in the fractional quantum Hall states [47,48,49,50].…”