Séminaire de l'INPHYNI: Defa Sun --- Daniel Carvalho de Salles

Dynamics of long rigid fibres in a turbulent channel flow (D. Sun)

Abstract:
The dynamics of fibres in turbulent flows is a topic of great concern in various applications, such as papermaking or dissemination of plastic debris in ocean. While previous studies mainly focused on relatively short fibres, we here investigate the dynamics of long rigid fibres in a turbulent channel flow, using a combination of experiments and direct numerical simulations. The length of the fibres considered is of the order of the channel half-height, which significantly enhances the wall-induced confinement effects. In particular, we focus on the pole-vaulting of the fibres at the wall and the associated enhancement of fibre tumbling rate.



---

Secure Delegated Sensing with polarization-entangled photons (D. Carvalho de Salles)

Abstract:
Secure quantum metrology combines quantum cryptography and metrology to enable confidential estimation of physical parameters at remote locations, with potential applications such as privacy-preserving remote medical monitoring. We experimentally implement a secure metrology protocol using entangled photon pairs, employing beam splitters for genuine random selection of measurement bases. To our knowledge, this is the first experimental implementation of a secure quantum metrology protocol incorporating this feature. Our measurements yielded a cryptographic bound of 99.5% on the quantum state fidelity and a phase estimation bias of 10⁻³π, demonstrating the feasibility of our approach.