Observation of interband Berry phase in laser-driven crystals.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38233521.
- Also identified by DOI 10.1038/s41586-023-06828-5 and PMC identifier 10830408.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Ever since its discovery<sup>1</sup>, the notion of the Berry phase has permeated all branches of physics and plays an important part in a variety of quantum phenomena<sup>2</sup>. However, so far all its realizations have been based on a continuous evolution of the quantum state, following a cyclic path. Here we introduce and demonstrate a conceptually new manifestation of the Berry phase in light-driven crystals, in which the electronic wavefunction accumulates a geometric phase during a discrete evolution between different bands, while preserving the coherence of the process. We experimentally reveal this phase by using a strong laser field to engineer an internal interferometer, induced during less than one cycle of the driving field, which maps the phase onto the emission of higher-order harmonics. Our work provides an opportunity for the study of geometric phases, leading to a variety of observations in light-driven topological phenomena and attosecond solid-state physics.