Phys.org September 8, 2021
Electrons in two-dimensional hexagonal materials have an extra degree of freedom that can be used to encode and process quantum information. An international team of researchers (India, Germany) demonstrated that both valley-selective excitation and valley-selective high-harmonic generation can be achieved in pristine graphene by using a combination of two counter-rotating circularly polarized fields, the fundamental and its second harmonic. Controlling the relative phase between the two colors allowed them to select the valleys where the electron–hole pairs and higher-order harmonics are generated. They described an all-optical method for measuring valley polarization in graphene with a weak probe pulse. The work offers a robust recipe to write and read valley-selective electron excitations in materials with zero bandgap and zero Berry curvature…read more. Open Access TECHNICAL ARTICLEÂ
Physical mechanism of valley polarization in graphene… Credit: Optica Vol. 8, Issue 3, pp. 422-427 (2021)Â