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キーワード:
General Relativity and Quantum Cosmology, gr-qc,High Energy Physics - Theory, hep-th
要旨:
We present a simple model of quantum cosmology based on the group field
theory (GFT) approach to quantum gravity. The model is formulated on a subspace
of the GFT Fock space for the quanta of geometry, with a fixed volume per
quantum. In this Hilbert space, cosmological expansion corresponds to the
generation of new quanta. Our main insight is that the evolution of a flat FLRW
universe with a massless scalar field can be described on this Hilbert space as
squeezing, familiar from quantum optics. As in GFT cosmology, we find that the
three-volume satisfies an effective Friedmann equation similar to the one of
loop quantum cosmology, connecting the classical contracting and expanding
solutions by a quantum bounce. The only free parameter in the model is
identified with Newton's constant. We also comment on the possible topological
interpretation of our squeezed states. This paper can serve an introduction
into the main ideas of GFT cosmology without requiring the full GFT formalism;
our results can also motivate new developments in GFT and its cosmological
application.
