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Quantum Hall Valley Splitters and a Tunable Mach-Zehnder Interferometer in Graphene
M Jo1, P Brasseur1, A Assouline1
1SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif sur Yvette Cedex France.
Physical Review Letters
|April 23, 2021
Summary
Researchers demonstrated tunable electronic beam splitters in graphene, enabling a fully controllable Mach-Zehnder interferometer. Graphene shows enhanced robustness against quantum decoherence compared to semiconductors.
Area of Science:
- Quantum optics
- Condensed matter physics
- Materials science
Background:
- Graphene is a promising material for electron quantum optics.
- A fully tunable and coherent electronic beam splitter is crucial but currently lacking.
Purpose of the Study:
- To demonstrate tunable electronic beam splitters in graphene.
- To realize and study a tunable electronic Mach-Zehnder interferometer in graphene.
Main Methods:
- Coupling quantum Hall edge channels with opposite valley polarizations in graphene.
- Tuning electronic transmission of beam splitters from zero to unity.
- Implementing a graphene p-n junction with independently controlled beam splitters.
Main Results:
- Demonstrated electronic beam splitters in graphene with tunable transmission.
- Realized a fully tunable electronic Mach-Zehnder interferometer by controlling beam splitters.
- Identified quantum interferences and studied their dependence on transmission and bias voltage.
Conclusions:
- Graphene electronic beam splitters enable tunable quantum interferometers.
- Graphene-based interferometers exhibit greater robustness against quantum decoherence than semiconductor counterparts.
- The findings suggest universal decoherence processes in 2D systems.
