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Light-Shaping of Valley States
Sangeeta Sharma1,2, John Kay Dewhurst3, Samuel Shallcross1
1Max-Born-Institute for Non-linear Optics and Short Pulse Spectroscopy, Max-Born Strasse 2A, 12489 Berlin, Germany.
Nano Letters
|December 15, 2023
Summary
Researchers discovered a new method to create valley states using light-shaping, not population imbalance. This opens doors for robust, ultrafast valleytronics in 2D materials.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Information
Background:
- Valley states, excitations at band extrema, are typically created by selective population using circularly polarized light.
- This established method relies on creating an imbalance in valley occupation.
Purpose of the Study:
- To demonstrate an alternative method for creating valley states.
- To explore valley states characterized by valley current rather than population imbalance.
Main Methods:
- Utilizing "light-shaping" in momentum space to control the charge distribution within valleys.
- Investigating valley states generated through controlled momentum-space light profiles.
Main Results:
- Demonstrated valley states characterized by valley current, not population difference.
- Showcased robustness to quantum decoherence.
- Achieved lossless toggling of valley states with femtosecond laser pulses.
- Enabled valley-contrasting excitation in gapped and gapless materials.
Conclusions:
- Introduced a novel approach to generate valley states via light-shaping.
- Established the potential for robust, ultrafast, and switchable valleytronics.
- Broadened the applicability of valleytronics to diverse 2D materials.
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