**Entanglement in Analogue Gravity**

*Can quantum effects in curved spacetimes be simulated in compact, laboratory-based experimental setups?*Following the formal analogy between quantum field theory on curved spacetimes and classical fluid systems [Unruh, Phys. Rev. D

**14**, 870 (1976)], this question has captivated researchers for decades, see e.g. [Barceló, Liberati, and Visser, Living Rev. Relativity

**8**, 12 (2005)] for a recent review. A central aim in such studies is the observation of radiation that can be associated to quantum pair creation processes, e.g., to the Hawking-, Unruh- and the dynamical Casimir effect. All of these effects rely on similar mechanisms in quantum field theory, i.e., particle creation due to time-dependent gravitational fields and boundary conditions, or the presence of horizons.We investigate the possibility to generate quantum-correlated quasi-particles utilizing such analogue gravity systems. The quantumness of these correlations is a key aspect of analogue gravity effects and their presence allows for a clear separation between classical and quantum analogue gravity effects.

However, experiments in analogue systems, such as Bose-Einstein condensates, and shallow water waves, are always conducted at non-ideal conditions, in particular, one is dealing with dispersive media at nonzero temperatures. In [Bruschi, Friis, Fuentes,Weinfurtner, New J. Phys.

A presentation can be downloaded here [pdf].

**15**, 113016 (2013)] we analyze the influence of the initial temperature on the entanglement generation in analogue gravity phenomena. We lay out all the necessary steps to calculate the entanglement generated between quasi-particle modes and we analytically derive an upper bound on the maximal temperature at which given modes can still be entangled. We further investigate a mechanism to enhance the quantum correlations. As a particular example we analyze the robustness of the entanglement creation against thermal noise in a sudden quench of an ideally homogeneous Bose-Einstein condensate, taking into account the super-sonic dispersion relations.A presentation can be downloaded here [pdf].