Saikat Nandi, Axel Stenquist, Asimina Papoulia, Edvin Olofsson, Laura Badano, Mattias Bertolino, David Busto, Carlo Callegari, Stefanos Carlström, Miltcho B Danailov, Philipp V Demekhin, Michele Di Fraia, Per Eng-Johnsson, Raimund Feifel, Guillaume Gallician, Luca Giannessi, Mathieu Gisselbrecht, Michele Manfredda, Michael Meyer, Catalin Miron, Jasper Peschel, Oksana Plekan, Kevin C Prince, Richard J Squibb, Marco Zangrando, Felipe Zapata, Shiyang Zhong, Jan Marcus Dahlström
Quantum entanglement between the degrees of freedom encountered in the classical world is challenging to observe due to the surrounding environment. To elucidate this issue, we investigate the entanglement generated over ultrafast timescales in a bipartite quantum system comprising two massive particles: a free-moving photoelectron, which expands to a mesoscopic length scale, and a light-dressed atomic ion, which represents a hybrid state of light and matter. Although the photoelectron spectra are measured classically, the entanglement allows us to reveal information about the dressed-state dynamics of the ion and the femtosecond extreme ultraviolet pulses delivered by a seeded free-electron laser...
April 19, 2024: Science Advances