### Conveners

#### R3-3 Quantum Theory (DTP) / Théorie quantique (DPT)

- Hubert de Guise ()

The state of a quantum system evolves according to the Schrödinger equation. Often, one is interested in the behaviour of parts of a whole system only. Such parts are called open quantum systems, as they exchange energy, matter, information with their surroundings. The dynamics of open systems is very complicated. They are a central topic of research in many theoretical and applied fields of...

The creation and annihilation of particles is a fundamental feature of relativistic quantum fields. A famous example of this is provided by Schwinger’s 1951 prediction that the vacuum is unstable to particle-antiparticle production if a static electric field is applied to it. In this talk we examine the classical field limit of Schwinger pair production by mapping the Klein-Gordon equation...

In optics, caustics are bright, sharp lines and shapes created by the natural focusing of light. Some examples include rainbows, the wavy lines on the bottom of swimming pools and the patterns produced by gravitational lensing. The intensity at a caustic diverges in the classical ray theory, but can be smoothed by taking into account the wave nature of light. In this work we consider a new...

Gravitational tidal forces conceal very interesting effects when combined with the extended nature of the wavefunction of a freely-falling quantum particle. The reason being that inertial properties of the particle get then mixed with the gravitational effects in such a way that, as in classical mechanics, the ratio between the gravitational mass and the inertial mass emerges. The equivalence...

Combining quantum and classical degrees of freedom provides a useful approximation in many practical applications. Examples include the study of quantum particles in a classical external potential (textbook quantum mechanics), or quantum field theory on a classical curved background. In these examples, only the classical affects the quantum, but not the other way around. If these...

This talk aim to discuss the scattering of particles on quantum superposed states. The fact that one of the initial states is in a superposition implies that the plane wave approximation is not valid anymore which is what we usually do. This will lead to the introduction of Wigner function and a formalism to describe this situation.

We will apply this new formalism to the question of...