Regensburg 2025 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 9: Poster

MM 9.6: Poster

Montag, 17. März 2025, 18:30–20:30, P1

Ultrafast phonon-mediated dephasing of color centers in hexagonal boron nitride probed by electron beams — •Masoud Taleb¹, Mario Hentschel³, Harald Giessen³, and Nahid Talebi^{1, 2} — ¹Institute of Experimental and Applied Physics, Kiel University, 24098 Kiel, Germany — ²Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, 24118 Kiel, Germany — ³4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70569 Stuttgart, Germany

Defect centers in hexagonal boron nitride (hBN) have gained significant interest as room-temperature single-photon sources, with strong coupling to phonons evident in their photoluminescence and cathodoluminescence spectra. Despite extensive studies, the electron-phonon coupling dynamics and phonon-mediated dephasing of these centers remain underexplored. In this study we experimentally employed an electron-driven photon source (EDPHS) to generate a coherent superposition of phonon states, with the delay between electron and photon pulses controlled to measure dephasing times. The findings reveal an ultrafast dephasing time of 200 fs and a radiative decay of 585 fs at room temperature, contradicting other optical techniques reporting a decay of a few nanoseconds. This rapid dephasing is attributed to the efficient excitation of coherent phonon-polaritons in hBN by electron beams. The research demonstrates the capability of sequential CL spectroscopy for probing the ultrafast dynamics of single emitters in quantum materials, facilitating future applications in quantum networks and devices.

Keywords: Light-Matter interaction; electron-driven photon sources; cathodoluminescence spectroscopy