Two physicists (a female and male) working on a lab experiment

ALP Seminar: Single atom-light interaction: from strong coupling to free-space light scattering

Seminars and colloquia
Simpkins Lee

Luke Masters (Humboldt University, Berlin)

Seminar series
ALP seminar
Knowledge of physics?
Yes, knowledge of physics required
For more information contact


The interaction of light with a single two-level emitter is the most fundamental process in quantum optics, and is key to many quantum applications. In this talk, I will present two distinct experiments that investigate this important setting [1, 2]. Firstly, the demonstration of strong coupling of a single atom to a whispering-gallery-mode microresontor was realised by generating a two-colour magic wavelength optical trap close to the resonator’s surface, and by measurement of a vacuum Rabi-splitting in the excitation spectrum of the coupled atom-resonator system. This first demonstration of stable and controlled interaction of a single atom with a whispering-gallery-mode in the strong coupling regime opens up the route towards the implementation of quantum protocols and applications that harvest the chiral atom-light interaction present in this class of resonators. In a second, more recent experiment, the light scattering of a single optically trapped atom in free-space was studied in detail. The measured photon statistics could be tuned from perfect antibunching to bunching, dependent on the setting of a narrowband optical filter in the detection path. These results offer insight into the scattering of two photons by a single two-level quantum emitter, and verify the picture that photon anticorrelations in resonance fluorescence can be thought of as arising from quantum interference between the coherent and incoherent two-photon scattering amplitudes.

[1] E. Will et al., Phys. Rev. Lett. 126, 233602 (2021)

[2] L. Masters et al., Nat. Phot. (2023)