Mainz 2017 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 10: Quantum Effects: QED II

Q 10.6: Talk

Monday, March 6, 2017, 18:15–18:30, P 4

Collective magnetic splitting in single-photon superradiance — •Xiangjin Kong and Adriana Pálffy — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

In an ensemble of identical atoms, cooperative effects like superradiance may alter the decay rates and the transition energies may be shifted from the single-atom value by the so-called collective Lamb shift. While such effects in ensembles of two-level systems are well understood, realistic multi-level systems are more difficult to handle.

Here, we present a quantitative study of systems of atoms or nuclei under the action of an external magnetic field, where a collective contribution to the level shifts appears that can amount to seizable deviations from the single-atom Zeeman or magnetic hyperfine splitting. We develop a formalism to describe single-photon superradiance in multi-level systems and identify three parameter regimes, two of which present measurable deviations in the radiation spectrum compared to the case of single-atom magnetic-field-induced splitting [1]. Only one of these regimes has been so far confirmed experimentally in nuclear condensed-matter systems [2]. Finally, we show that all three regimes should be realizable in planar x-ray cavities with an embedded nuclear layer [3] under experimental parameters available today. Our findings give new and unexpected insights on the collective behaviour of optical and x-ray systems in magnetic fields.

[1] X. Kong and A. Pálffy, arXiv:1606.02988 (2016).

[2] R. Röhlsberger et al., Nature 482, 199 (2012).

[3] X. Kong and A. Pálffy, Phys. Rev. Lett. 116, 197402 (2016).