Analogue models of gravity
Quantum field theories on curved spacetime represent a first step towards including the effects of gravity into the dynamics of quantum matter fields [1]. Among the most celebrated predictions of this theory are the evaporation of black holes in the form of a thermal Hawking radiation [2], or the particle creation by an expanding, or more generally non-stationary universes [3,4]. In his seminal paper [5], Unruh realized that these phenomena are not relevant only to gravitational systems, but are instead a purely kinematical effect of quantum fields living on a (possibly effective) curved spacetime.
Relying on this seminal idea, the research field of analogue models of gravity has flourished over the past few decades, giving rise to a surge of both theoretical and experimental studies on the origin of the Hawking radiation and cosmological particle creation in a multitude of analogue systems [6]. In this group we have explored the rich phenomenology of analogue gravity in both optical [7-9], as well as condensed matter systems [10]. The long term perspective of our research in this field aims towards the development of a self-consistent theory of a quantum field and its back-ground spacetime. This takes into account the effects of the back-reaction of the particles created out of the vacuum state of a quantum field onto the dynamics of the background spacetime.
References
[1] N. D. Birrell and P. C. W. Davies, Quantum Fields in Curved Space, Cambridge University Press (1982)
[2] S. W. Hawking. Nature, 248 30–31 (1974)
[3] L. Parker, Phys. Rev., 183 1057 (1969)
[4] L. Parker, Phys. Rev. D, 3 346 (1971)
[5] W. G. Unruh, Phys. Rev. Lett., 46 1351–1353 (1981)
[6] C. Barcelo et al., Living Rev. Rel., 14 3 (2011)
[7] Blackbody Emission from Light Interacting with an Effective Moving Dispersive Medium, Mihail Petev, Niclas Westerberg, Daniel Moss, Eleonora Rubino, C. Rimoldi, Sergio L. Cacciatori, Francesco Belgiorno, and Daniele Faccio; Phys. Rev. Lett. 111, 043902 (2013)
[8] Experimental quantum cosmology in time-dependent optical media, Niclas Westerberg, S Cacciatori, Francesco Belgiorno, Francesco Dalla Piazza and Daniele Faccio; New J. Phys. 16, 075003 (2014)
[9] Optical analogues of the Newton–Schrödinger equation and boson star evolution, Thomas Roger, Calum Maitland, Kali Wilson, Niclas Westerberg, David Vocke, Ewan M. Wright and Daniele Faccio; Nature Communications 7, 13492 (2016)
[10] Curved spacetime from interacting gauge theories, Salvatore Butera, Niclas Westerberg, Daniele Faccio, and Patrik Ohberg; Class. Quantum Grav. 36, 034002 (2019)