Sémaire de l'INPHYNI: Alexandre VIGNA BRUMMER (Fluides) / Jean-Marcel Nazon (Atomes)

Alexandre Vigna-Brummer - Flowing soap films

Foam drainage, driven by liquid flow through menisci, strongly influences foam lifetime. Menisci form at junctions of thin liquid films and receive flux due to Laplace pressure differences, often ignored in drainage models. We investigated this flux using large vertical soap films (150 × 250 mm²) sustained by a syringe pump. Film thickness was measured by interferometry, and isolated menisci were created with inserted objects of varying geometry and size. Results show a transition between a hydrostatic regime with negligible exchange and a flowing regime where film flux enlarges the meniscus. An analytical model accounts for this flux and predicts a characteristic length scale.

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Jean-Marcel Nazon - Dynamic properties of Bragg reflection in ordered 1D cold atomic vapors

We investigate the photonic properties of a one-dimensional array of cold atoms. Such a system enables the opening of a photonic band gap, which results in efficient reflection of light by the atoms. While the stationary properties of this phenomenon are well established, we have explored its temporal dynamics for the first time. By abruptly switching off the incident beam, we observe two striking effects: a transient light “flash” and a superradiant decay of the reflected signal. We now aim to focus on the slowing down of the group velocity at the edge of the photonic band gap