An on/off Berry phase switch in circular graphene resonators

The phase of a quantum state may not return to its original value after the system’s parameters cycle around a closed path; instead, the wave function may acquire a measurable phase difference called the Berry phase. Berry phases typically have been accessed through interference experiments. Here, w...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2017-05, Vol.356 (6340), p.845-849
Main Authors: Ghahari, Fereshte, Walkup, Daniel, Gutiérrez, Christopher, Rodriguez-Nieva, Joaquin F., Zhao, Yue, Wyrick, Jonathan, Natterer, Fabian D., Cullen, William G., Watanabe, Kenji, Taniguchi, Takashi, Levitov, Leonid S., Zhitenev, Nikolai B., Stroscio, Joseph A.
Format: Article
Language:English
Subjects:
Angular momentum
ATOMIC AND MOLECULAR PHYSICS
Circularity
Conductivity
Electronic structure
Electrons
Fermions
Graphene
Magnetic fields
Optoelectronic devices
P-n junctions
Phase shift
Quantum mechanics
Resonators
S parameters
Scanning
Spectroscopy
Switches
Turning behavior
Wave functions
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Summary:The phase of a quantum state may not return to its original value after the system’s parameters cycle around a closed path; instead, the wave function may acquire a measurable phase difference called the Berry phase. Berry phases typically have been accessed through interference experiments. Here, we demonstrate an unusual Berry phase–induced spectroscopic feature: a sudden and large increase in the energy of angular-momentum states in circular graphene p-n junction resonators when a relatively small critical magnetic field is reached. This behavior results from turning on a π Berry phase associated with the topological properties of Dirac fermions in graphene. The Berry phase can be switched on and off with small magnetic field changes on the order of 10 millitesla, potentially enabling a variety of optoelectronic graphene device applications.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aal0212