Semiclassical States in Quantum Cosmology: Bianchi I Coherent States

Abstract

We study coherent states for Bianchi type I cosmological models, as examples of semiclassical states for time-reparametrization invariant systems. This simple model allows us to study explicitly the relationship between exact semiclassical states in the kinematical Hilbert space and corresponding ones in the physical Hilbert space, which we construct here using the group averaging technique. We find that it is possible to construct good semiclassical physical states by such a procedure in this model; we also discuss the sense in which the original kinematical states may be a good approximation to the physical ones, and the situations in which this is the case. In addition, these models can be deparametrized in a natural way, and we study the effect of time evolution on an "intrinsic" coherent state in the reduced phase space, in order to estimate the time for this state to spread significantly.

arXiv comment21 pages, 1 figure; Version to be published in CQG; The discussion has been slightly reorganized, two references added, and some typos corrected

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• Classical and Quantum Features of the Mixmaster Singularity
• Semiclassical States for Constrained Systems
• Coherent semiclassical states for loop quantum cosmology
• On the Semiclassical Limit of Loop Quantum Cosmology
• Semiclassical states for quantum cosmology
• Perturbation theory in covariant canonical quantization
• General Relativity as Classical Limit of Evolutionary Quantum Gravity
• Coherent states for fractional powers of the harmonic oscillator Hamiltonian