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PhD position: Subradiance and applications to quantum technologies

Laboratory: Institut de Physique de Nice (INPHYNI), Valbonne, France
Contacts:
– William Guerin (william.guerin@inphyni.cnrs.fr)
– Robin Kaiser (robin.kaiser@inphyni.cnrs.fr)
Team webpage: https://inphyni.cnrs.fr/sites/teams/cold-atoms/
Grant: The PhD fellowship is provided for three years by an ANR funding via the European QuantERA project « Photon-Atom Cooperative Effects at Interfaces » (PACE-IN).
Starting date: September 2020.
Subject:
Wave propagation in diffusive media is a topic of interest for mainly domain (medical imaging, acoustic, seismology, stellar physics…). The experiments performed in our group at INPHYNI use an original medium: a cloud of laser-cooled atoms. The very peculiar properties of this diffusive medium (very narrow resonances, internal quantum structure of the scatterers, mechanical effects of light on the atoms, quantum effects…) give rise to a very rich physics. In this context, one of the subjects that we are studying is cooperative scattering. When a photon is sent onto an atomic ensemble, it interacts collectively with all the atoms, and not only with one of them. This produces measurable changes in the scattering rate, the emission diagram of the temporal dynamics. We study these cooperative effects experimental as well as theoretically. The subject of the PhD thesis deals with one of these effects, subradiance, which has been experimentally observed in our team [1], 60 years after its first prediction [2]. Subradiance is the suppression of spontaneous emission due to the anti-synchronization of the atomic dipoles. It manifests by a reduced decay rate, i.e. a longer lifetime of light in the sample (see figure). Recently, we have performed several complementary studies on subradiance, which allowed us to reach a good understanding of this effect [3,4,5].

Now we want to study the potential applications of subradiance to photonic or/and quantum technologies, such as quantum memories, generation and characterization of nonclassical state of light, or the design of new photonic components. This work will take place in the framework of a European collaboration involving other experimental teams working on complementary platforms (trapped ions) and theoreticians. More precisely, and on the short term, we plan working on designing protocols for maximizing the population of subradiant states and we plan studies of the robustness of subradiant states against decoherence mechanisms. On longer term we’ll test ideas that come up within the consortium. Short and/or long stay at our European partner institutions will be possible and encouraged.

Requirements:

We’re looking for a serious and motivated student with some significant experience (such as a Master thesis) in optical or atomic physics experiments. Speaking English fluently is expected. Speaking French is recommended but not necessary.
Candidates should apply by email to William Guerin and Robin Kaiser and provide their CV, their marks/grade during their Master studies, and at least one contact for recommendation. The position will stay open until filled.

References :
[1] Subradiance in a large cloud of cold atoms, W. Guerin, M. O. Araujo, R. Kaiser, Phys. Rev. Lett. 116,
083601 (2016).
[2] Coherence in spontaneous radiation processes, R. H. Dicke, Phys. Rev. 93, 99 (1954).
[3] Population of collective modes in light scattering by many atoms, W. Guerin, R. Kaiser, Phys. Rev. A 95,
053865 (2017)
[4] Subradiance and radiation trapping in cold atoms, P. Weiss, M. O. Araujo, R. Kaiser, W. Guerin,
New J. Phys. 20, 063024 (2018).
[5] Robustness of Dicke subradiance against thermal decoherence, P. Weiss, A. Cipris, M. O. Araujo,
R. Kaiser, W. Guerin, Phys. Rev. A 100, 033833 (2019).

 

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