Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 31: Quantum Effects (QED)

Q 31.7: Talk

Tuesday, March 6, 2018, 15:30–15:45, K 1.013

A derivation of the resonance fluorescence spectrum with the resolvent-operator formalism — •Vincent Debierre and Zoltán Harman — Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg

It is known that the spectrum of the light scattered by a two-level atom (the so-called Mollow spectrum) exhibits very different profiles in different intensity regimes. In particular, the incoherently scattered fraction of the incoming light is subdominant at low intensities and dominant at high intensities. Mollow has shown that the incoherent part takes over when the Rabi frequency of the light-atom interaction becomes larger than the natural linewidth of the excited atomic state. We derived [V. Debierre and Z. Harman, Phys. Rev. A 96, 043835 (2017)] the Mollow spectrum in the resolvent operator formalism. The derivation is based on the construction of a master equation from the resolvent operator of the atom-field system. We show that, for electric dipole transitions, the natural linewidth of the excited atomic level remains essentially unmodified, to a very good level of approximation, even in the strong-field regime, where Rabi flopping becomes relevant inside the self-energy loop that yields the linewidth, ensuring that the obtained master equation and the spectrum derived matches that of Mollow. On the other hand, for non-electric dipole transitions (that can still be treated within the framework of the two-level approximation), our formalism predicts important modifications to the lifetime of the excited state in the strong-driving case.