We investigate the temperature and voltage dependence of the quantum interference in an electronic MachZehnder interferometer using edge channels in the integer quantum-Hall regime. The amplitude of the interference fringes is significantly smaller than expected from theory; nevertheless the functional dependence of the visibility on temperature and bias voltage agrees very well with theoretical predictions. Superimposed on the Aharonov-Bohm ͑AB͒ oscillations, a conductance oscillation with a six times smaller period is observed. The latter depends only on gate voltage and not on the AB phase, and may be related to single electron charging.Electron interferences in mesoscopic conductors manifest themselves in conductance oscillations which are h / e periodic in the magnetic field B. 1 In conventional metals the visibility I of these Aharonov-Bohm ͑AB͒ oscillations typically amounts to I = G 0 / G Ӎ 10 −3 , where G is the conductance of the sample and G 0 =2e 2 / h the conductance quantum. The visibility can be enhanced to I Ӎ 0.1 by reducing the number of conductance channels, e.g., in nanostructures based on two-dimensional electron systems 2,3 containing only a small number of conductance channels. Recently an electronic analog 4 of the well-known optical Mach-Zehnder interferometer ͑MZI͒ was realized, which employs the onedimensional edge channels in the integer quantum Hall regime. 5 In these devices single channel interference can be realized, while backscattering processes are suppressed. This results in measured visibilities up to I Ӎ 0.6. Such devices open a path for the realization of fundamental two-particle interference experiments in the spirit of Hanbury-Brown and Twiss, 6 as recently proposed. 7 We have realized MZIs similar to those in Ref. 5. A quantum point contact ͑QPC͒ is used to partition an edge channel leaving contact S in two paths. After propagation of the edge channel along the inner and outer edge of a ring-shaped mesa, the two paths are brought to interference at a second QPC, resulting in two output channels D1 and D2 of the interferometer ͑see Fig. 1͒. The phase of the two partial waves can be changed both by magnetic field and by an electrostatic gate G. The measured visibility is much smaller than expected from theory 8 and reported in Ref. 5. Despite this quantitative disagreement, the functional dependence of I on T and V bias fits very well the simple model of Ref. 8. In addition to the AB oscillations we found another type of conductance oscillations, which have a significantly smaller period in gate voltage when compared to the AB period.The mesa was prepared through wet etching of a modulation doped GaAs/ Ga x Al 1−x As heterostructure containing a two-dimensional electron system ͑2DES͒ 90 nm below the surface. At 4 K, the unpatterned 2DES density and mobility were n = 2.0ϫ 10 15 m −2 and = 206 m 2 / ͑V s͒, respectively. Using standard electron beam lithography techniques, we prepared split gates connected by air bridges, defining QPCs of 500 nm length and 220 nm gap width. Th...

We study the visibility of Aharonov-Bohm interference in an electronic Mach-Zehnder interferometer in the integer quantum Hall regime. The visibility is controlled by the filling factor and is observed only between Ϸ 2.0 and 1.0, with an unexpected maximum near = 1.5. Three energy scales extracted from the temperature and voltage dependences of the visibility change in a very similar way with the filling factor, indicating that the different aspects of the interference depend sensitively on the local structure of the compressible and incompressible strips forming the quantum Hall edge channels.

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Magneto-optical phenomena such as the Faraday and Kerr effects play a decisive role for establishing control over polarization and intensity of optical fields propagating through a medium. Intensity effects where the direction of light emission depends on the orientation of the external magnetic field are of particular interest as they can be used for routing the light. We report on a new class of transverse emission phenomena for light sources located in the vicinity of a surface, where directionality is established perpendicularly to the externally applied magnetic field. We demonstrate the routing of emission for excitons in a diluted-magnetic-semiconductor quantum well. The directionality is significantly enhanced in hybrid plasmonic semiconductor structures 1 arXiv:1712.05703v1 [cond-mat.mtrl-sci]