Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 35: Transport: Nanoelectronics I - Quantum Dots, Wires, Point Contacts 3

TT 35.11: Vortrag

Donnerstag, 28. Februar 2008, 16:45–17:00, H 3010

Bulk-edge coupling in the non-abelian ν=5/2 quantum Hall interferometer — •Bernd Rosenow¹, Bertrand I. Halperin¹, Steven H. Simon², and Ady Stern³ — ¹Physics Department, Harvard University, Cambridge, MA 02138 — ²Lucent-Alcatel Bell Laboratories, Murray Hill NJ, 07974 — ³Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel

Recent schemes for probing non-abelian statistics in the ν=5/2 quantum Hall effect are based on geometries where current-carrying quasiparticles flow along edges that encircle N_qp bulk quasiparticles, which are localized. Here we consider one such scheme, the Fabry-Perot interferometer. In the limit of weak back-scattering, when N_qp is even the two back-scattering amplitudes interfere coherently, while when N_qp is odd they are incoherent, and thus do not interfere. In the former case, the back-scattered current oscillates with the area of the cell, while in the latter case it does not. This difference reflects the non-abelian nature of the quasiparticles.

In a real system, some degree of coupling between the edge and quasiparticles localized in the bulk is unavoidable. One may suspect that such a coupling would blur the distinction between bulk and edge quasiparticles and endanger the possibility of observing the even-odd effect. We find that at weak coupling the interference signal is indeed degraded, while for strong enough coupling the bulk quasiparticle becomes essentially absorbed by the edge and the even-odd effect survives. Furthermore, we find that the strength of the coupling can be tuned by the source-drain voltage.