Casimir effect in a nonlinear crystal

Casimir effect in a nonlinear crystal

Stage de M2 - numérique

Casimir effect in a nonlinear crystal


Photonic quantum fluids have been recently identified as an outstanding system for quantum sim- ulation, ranging from condensed matter to astrophysics [1]. Through the mergence of many-body physics and nonlinear optics, fluids of light reveal quantum hydrodynamic features of light when it propagates in a nonlinear media. One of the most remarkable evidence of light behaving as an interacting fluid is its ability to carry itself as a superfluid. At the Institut de Physique de Nice, we developed a state-of-the-art experimental set-up based
on a versatile photonic platform and recently reported a direct experimental detection of the transition to superflu- idity in the flow of a fluid of light past an obstacle in a bulk nonlinear crystal.
In this cavityless all-optical system, we extract a direct optical analog of the drag force exerted by the fluid of light and measure the associated displacement of the obstacle. We observe that both quantities drop to zero in the super- fluid regime [2].

Fig. 1 – Transition from a dissipative (left) to a superfluid (right) regime for a fluid of light propagating in a nonlinear crystal.

In this vein, we now target the study and the observation of optical Casimir forces in a fluid of light. The original quantum Casimir effect consists in an attracting force appearing between two plates, due to vacuum fluctuations. Here, in the photonic context, the fluctuations will be driven by an optical speckle, and refractive index barriers play the role of the material plates. In this configuration, we aim at measuring the displacement of such optical barriers.

[1] I. Carusotto and C. Cuiti, “Quantum fluids of light”, Rev. Mod. Phys. 85, 299 (2013).
[2] C. Michel et al, “Superfluid motion and drag-force cancellation in a fluid of light”, Nat. Commun. 9, 2108 (2018).


As a first step, the proposed project will focus on an extensive numerical study of the Casimir effect in a fluid of light. The student will develop a numerical code in order to accurately estimate the optical barrier displacement.


This project is at the interface between quantum hydrodynamics, nonlinear optics and transport in complex media. We are looking for highly motivated applicants with knowledge in at list one of these topics. The duration of the internship may vary from 3 to 6 months. The internship gratification is about 450 € net /month.

Contact & info

Claire Michel :, +33 (0)4 92 07 67 88

Matthieu Bellec :, +33 (0)4 92 07 67 88

Nicolas Cherroret :, +33 (0)1 44 27 44 00

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