Control of the transmission phase in an asymmetric four-terminal Aharonov-Bohm interferometer

Sven S. Buchholz, Saskia F. Fischer, Ulrich Kunze, Matthew Bell, Dirk Reuter, and Andreas D. Wieck

Phys. Rev. B 82, 045432 – Published 30 July 2010

Abstract

Phase sensitivity and thermal dephasing in coherent electron transport in quasi-one-dimensional (1D) waveguide rings of an asymmetric four-terminal geometry are studied by magnetotransport measurements. We demonstrate the electrostatic control of the phase in Aharonov-Bohm resistance oscillations and investigate the impact of the measurement circuitry on decoherence. Phase rigidity is broken due to the ring geometry: orthogonal waveguide cross junctions and 1D leads minimize reflections and resonances between leads allowing for a continuous electron transmission phase shift. The measurement circuitry influences dephasing: thermal averaging dominates in the nonlocal measurement configuration while additional influence of potential fluctuations becomes relevant in the local configuration.