University of Freiburg

Institute of Physics

**Quantum Optics and Statistics**

**Entanglement and quantum information in analogue black holes : analogue Hawking radiation in Bose-Einstein condensates (BECs)**

In an acoustic analogue system, as the ones obtained in **BECs**, a **transonic fluid flow **(i.e. a flow which is supersonic in a region of space, and subsonic elsewhere) is **experimentally **realized in order to model a gravitational black hole. Quantum fluctuations of the sound field induce emission of Hawking quanta away from the acoustic horizon. This radiation is correlated to a “partner” which falls inside the analogous black hole. This is why studying this phenomenon in Bose-Einstein condensates allows for a better understanding of **multipartite entanglement **and **information transport**. The topic therefore belongs to the very active and stimulating area of research called “**quantum simulators**”.

The project should mainly focus on the study of the two phenomena of backreaction and information entropy transport. Indeed, the theoretical background set by the **Gross-Pitaevskii equation **allows for the inquiry in BECs of **non-linear quantum effects **induced by the emission of analogue Hawking radiation on the transonic configuration of the system itself, that is on the acoustic horizon (**backreaction**). Furthermore, studying the **entanglement **between the analogue Hawking radiation and the acoustic black hole in a BEC will allow to address the problem of the **restitution**, by the acoustic black hole, **of the absorbed information **through the thermal Hawking radiation (**information entropy transport**). Such a study can be undertaken by modeling the **information dynamics in an open system. **Studying analogue systems in BECs thus **raises both theoretical and experimental issues for controlled dynamics of atomic systems.**

**Supervisors: **

Andreas Buchleitner (Quantum Optics and Statistics, Freiburg University)

Nicolas Pavloff (LPTMS, Paris-Saclay)