Physics. Creating and probing electron whispering-gallery modes in graphene

Area of Science:

• Condensed Matter Physics
• Quantum Optics
• Materials Science

Background:

• Designing high-finesse resonant cavities for electronic waves is challenging due to short electron coherence lengths in solids.
• Previous methods for confining electronic waves involved adatoms on metallic surfaces.

Purpose of the Study:

• To demonstrate a new approach for creating electronic wave resonators inspired by acoustic whispering galleries.
• To utilize graphene's unique electronic properties for wave confinement.

Main Methods:

• Creating whispering-gallery mode (WGM) resonators by inducing circular pn junctions in graphene using a scanning tunneling probe.
• Utilizing a back-gated graphene device to tune resonator size and carrier concentration.
• Leveraging graphene's gate-tunable, light-like charge carriers.

Main Results:

• Successfully created tunable WGM resonators in graphene.
• Demonstrated control over resonator size and carrier concentration.
• Observed WGM-type confinement and associated resonances.

Conclusions:

• The developed WGM resonators represent a novel addition to quantum electron-optics.
• This technique offers a promising pathway for the development of electronic lenses and resonators.