Detecting Entanglement from Macroscopic Measurements of the Electric Field and Its Fluctuations.

To address the outstanding task of detecting entanglement in large quantum systems, entanglement witnesses have emerged, addressing the separable nature of a state. Yet optimizing witnesses, or accessing them experimentally, often remains a challenge. We here introduce a family of entanglement witnesses for open quantum systems.

Analytical solution of SEIR model describing the free spread of the COVID-19 pandemic.

We analytically study the SEIR (Susceptible Exposed Infectious Removed) epidemic model. The aim is to provide simple analytical expressions for the peak and asymptotic values and their characteristic times of the populations affected by the COVID-19 pandemic.

Slow dynamics and subdiffusion in a non-Hamiltonian system with long-range forces.

Inspired by one-dimensional light-particle systems, the dynamics of a non-Hamiltonian system with long-range forces is investigated. While the molecular dynamics does not reach an equilibrium state, it may be approximated in the thermodynamic limit by a Vlasov equation that does possess stable stationary solutions. This implies that on a macroscopic scale the molecular dynamics evolves on a slow timescale that diverges with the system size.

Coherence effects in scattering order expansion of light by atomic clouds.

We interpret cooperative scattering by a collection of cold atoms as a multiple-scattering process. Starting from microscopic equations describing the response of N atoms to a probe light beam, we represent the total scattered field as an infinite series of multiple-scattering events. As an application of the method, we obtain analytical expressions of the coherent intensity in the double-scattering approximation for Gaussian density profiles.

Controlled Dicke subradiance from a large cloud of two-level systems.

Dicke superradiance has been observed in many systems and is based on constructive interferences between many scattered waves. The counterpart of this enhanced dynamics, subradiance, is a destructive interference effect leading to the partial trapping of light in the system. In contrast to the robust superradiance, subradiant states are fragile, and spurious decoherence phenomena hitherto obstructed the observation of such metastable states.