Ultrafast Saddletronics: Current and Charge Control at the M Point

Area of Science:

• Condensed Matter Physics
• Quantum Information Science
• Materials Science

Background:

• Low-energy valleys in 2D materials offer a route for ultrafast information writing using laser light.
• Excited charge at K or K* valleys represents fundamental quantum states (0 and 1).

Purpose of the Study:

• To demonstrate light-wave control over information states using saddle points in 2D materials.
• To explore the potential of saddle points for ultrafast information manipulation.

Main Methods:

• Utilizing linearly polarized light to excite saddle points in graphene.
• Investigating excitation in both subcycle strong field and multicycle pulse regimes.

Main Results:

• Linearly polarized light excites 2 out of 3 inequivalent M point saddles in graphene.
• The direction of the polarization vector determines the realized excited configurations.
• Saddle excitation is robust and creates "saddle polarized" states.

Conclusions:

• Saddle points, in addition to valleys, possess light-wave control over information states.
• Findings are applicable to graphene family and Xenes like stanene.
• Opens avenues for rich and ultrafast light-based manipulation of quantum matter.