D Ferraro et al 2010 New J. Phys. 12 013012 doi:10.1088/1367-2630/12/1/013012
Neutral modes' edge state dynamics through quantum point contacts
D Ferraro1, A Braggio2, N Magnoli1 and M Sassetti2
Show affiliationsThe dynamics of neutral modes for fractional quantum Hall states is investigated for a quantum point contact geometry in the weak-backscattering regime. The effective field theory introduced by Fradkin–Lopez for edge states in the Jain sequence is generalized to the case of propagating neutral modes. The dominant tunnelling processes are identified also in the presence of non-universal phenomena induced by interactions. The crossover regime in the backscattering current between tunnelling of single-quasiparticles and of agglomerates of p-quasiparticles is analysed. We demonstrate that higher-order cumulants of the backscattering current fluctuations are a unique resource to study quantitatively the competition between different carrier charges. We find that propagating neutral modes are a necessary ingredient in order to explain this crossover phenomenon.
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GENERAL SCIENTIFIC SUMMARY
Introduction and background. Under suitable conditions a two-dimensional electron gas, subjected to an intense magnetic field at very low temperature, shows the fractional quantum Hall effect: a peculiar state of matter. Here, low-energy excitations at the edge of the Hall bar are present with fractional charge and statistics. They can be studied via tunnelling through a quantum point contact. These excitations are represented in terms of bosonic fields; one related to the charge and the other, called neutral, responsible for the statistical properties. The role of the neutral field in the dynamics of the edge is still not completely understood.Main results. Our paper sheds light on the effects of neutral modes in the dynamics of edge states for a quantum point contact, focusing on current and noise behaviour. We show that neutral modes are essential to explain the crossover between tunnelling of single-quasiparticles and tunnelling of agglomerates of quasiparticles, also recently observed in experiments.
Wider implications. Understanding neutral mode dynamics in the edge state furthers comprehension of a broader spectrum of experimental data, also shedding new light on even more exotic phenomena that appear in the quantum Hall effect. This greater understanding may be relevant for quantum computation.
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Issue 1 (January 2010)
Received 29 October 2009
Published 15 January 2010
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Neutral modes' edge state dynamics through quantum point contacts
D Ferraro et al 2010 New J. Phys. 12 013012
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