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Gate-tunable quantum pathways of high harmonic generation in graphene
Soonyoung Cha1, Minjeong Kim1,2, Youngjae Kim3
1Center for Van der Waals Quantum Solids, Institute for Basic Science (IBS), Pohang, Republic of Korea.
Nature Communications
|November 5, 2022
Summary
Researchers resolved quantum pathways of massless Dirac fermions in graphene using electrostatic control and high-harmonic generation (HHG). This breakthrough enables ultrafast probing of quantum semimetals and their electronic structures with gate control.
Area of Science:
- Condensed Matter Physics
- Quantum Optics
- Materials Science
Background:
- High-harmonic generation (HHG) in solids probes electron dynamics via quantum pathways.
- Characterizing these pathways in semimetals is challenging due to the lack of a bandgap.
- Previous demonstrations were limited to semiconductors.
Purpose of the Study:
- To resolve quantum pathways of massless Dirac fermions in graphene under strong laser fields.
- To enable experimental characterization of electron dynamics in semimetals.
- To explore ultrafast electronic properties of quantum semimetals.
Main Methods:
- Combining electrostatic control of chemical potentials with high-harmonic generation (HHG) measurements.
- Utilizing strong laser fields to drive electrons through Bloch bands.
- Employing theoretical calculations to corroborate experimental findings.
Main Results:
- Quantum pathways of massless Dirac fermions in graphene were successfully resolved.
- Electrical modulation of HHG revealed quantum interference between interband excitation channels.
- Elliptically polarized laser fields were shown to efficiently drive Dirac fermions via coupled interband and intraband transitions.
Conclusions:
- This study provides a method for strong-laser-field tomography of Dirac electrons in quantum semimetals.
- The findings open avenues for investigating ultrafast electronics in semimetals with gate control.
- Enables all-optical ultrafast probing of coherent lightwave-driven processes and electronic structures.
