# Talks

Below, I list some of my past talks together with the slides I've used.

**A Universe in Heidelberg**

When quantum fields experience spacetime curvature, many fascinating phenomena arise. This includes cosmological particle production, which occurs when the spacetime metric is explicitly time-dependent. However, detecting this phenomenon in the night sky remains an open challenge. Following recent theoretical and experimental developments in Heidelberg, we report on a novel quantum field simulator to engineer a quantum field experiencing an expanding universe of positive as well as negative spatial curvature in a 2+1 dimensional Bose-Einstein condensate with adjustable trapping potential and interaction strength. We demonstrate the successful implementation by comparing novel analytical results to the propagation of acoustic excitations and, for the first time, observe cosmological particle production in the lab, in agreement with cosmological predictions.

**Relative entropic uncertainty relation for scalar quantum fields**

Entropic uncertainty is a well-known concept to formulate uncertainty relations for continuous variable quantum systems with finitely many degrees of freedom. Typically, the bounds of such relations scale with the number of oscillator modes, preventing a straight-forward generalization to quantum field theories. In this talk, we will present a way of overcoming this difficulty by introducing the notion of a functional relative entropy, which has a meaningful field theory limit. We will show the first entropic uncertainty relation for a scalar quantum field theory and illustrate that its bound remains finite also for an infinite number of oscillator modes.

**Entropic entanglement criteria in phase space**

Typically, entropic uncertainty relations and inseparability criteria are formulated for marginal distributions in phase space. In this talk, I discuss an approach based on the Husimi Q-distribution, which can be measured following the heterodyne detection protocol. The associated entropy, known as the Wehrl entropy, fulfills an entropic uncertainty relation and can be used to construct entanglement witnesses. In particular, I will discuss the Wehrl mutual information, which is a perfect entanglement witness for all pure states, and I will derive a general inseparability criterion based on the Wehrl entropy, which certifies entanglement in previously undetectable regions.