Coherent phonon flatband generated in GaAs/AlAs superlattices via layer-selective optical pumping

Year: 2025

Type: article

Abstract: Flatbands, characterized by their dispersionless energy levels in electronic, magnetic, and phononic systems, hold substantial potential for advancements in electronics and quantum information processing. Most flatbands exist in thermal equilibrium and cannot be easily created or annihilated externally, limiting their flexibility as switchable knobs for use in microelectronics and quantum applications. In our work, we demonstrate the generation of a coherent phonon flatband in a GaAs/AlAs superlattice using 800 nm femtosecond laser pulses. This coherent phonon flatband does not correspond to a phonon eigenmode at equilibrium and exhibits strong coupling with two branches of coherently excited longitudinal phonon modes. With molecular dynamics simulations, we show more generally that the coherent phonon flatband can be induced by coherently and spatially modulated optical excitations of superlattice structures. Our results highlight a pathway for coherent phonon flatband creation in the time domain that can be generalized to various superlattice systems, potentially inspiring the realization of coherent flatband generation of other quasiparticles. Above-bandgap femtosecond laser pulses generate a coherent phonon flatband in a GaAs/AlAs superlattice captured using ultrafast X-ray diffraction, providing a way to control atomic vibrations for future electronic and quantum technologies.

Source: Nature Communications

DOI: 10.1038/s41467-025-62817-4

Institutions: The University of Texas at Austin, Argonne National Laboratory, University of Nevada, Reno, Chinese Academy of Sciences, Institute of High Energy Physics, Harbin Institute of Technology, Advanced Photon Source, Paul Scherrer Institute

Language: English

Topic: Laser-Matter Interactions and Applications

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $6,990

Funders: National Science Foundation, U.S. Department of Defense, U.S. Department of Energy, European Commission, National Natural Science Foundation of China, Paul Scherrer Institut, Directorate for Engineering, Office of Science, Multidisciplinary University Research Initiative, Division of Materials Research, Division of Chemical, Bioengineering, Environmental, and Transport Systems, Division of Electrical, Communications and Cyber Systems, Basic Energy Sciences, Laboratory Directed Research and Development, Argonne National Laboratory

OpenAlex ID: W4414557028