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Q: Fachverband Quantenoptik und Photonik

Q 69: Post-Deadline Session

Q 69.1: Vortrag

Freitag, 9. März 2018, 10:30–10:45, K 1.020

Experimental Evidence of Quantum Radiation Reaction in Aligned Crystals — •Tobias Wistisen and Antonino Di Piazza — Max-Planck-Institut für Kernphysik, Heidelberg, Germany

Radiation reaction is the influence of the electromagnetic field emitted by a charged particle on the dynamics of the particle itself. Classical theoretical approaches to radiation reaction lead to physically inconsistent equations of motion. In addition, radiation-reaction effects have never been measured, which has prevented a complete understanding of this problem [1]. Here I will talk about experimental results obtained to address this issue [2]. We measured radiation emission spectra from ultrarelativistic positrons in silicon in a regime where both quantum and radiation-reaction effects dominate the dynamics of the positrons. We found that each positron emits multiple photons with energy comparable to its own energy, revealing the importance of quantum photon recoil. Moreover, the shape of the emission spectra indicates that photon emissions occur in a nonlinear regime where positrons absorb several quanta from the crystal field. This experiment is the first fundamental test of quantum electrodynamics in a new regime where the dynamics of charged particles is strongly influenced not only by the external electromagnetic fields but also by the radiation-field generated by the charges themselves and where each photon emission potentially reduces the energy of the charge by a significant amount.

[1] A. Di Piazza et al., Rev. Mod. Phys. 84, 1177 (2012)

[2] T. N. Wistisen, A. Di Piazza, H. V. Knudsen, and U. I. Uggerhøj, arXiv:1704.01080, 2017.