Star product approach for Loop Quantum Cosmology

TL;DR

This paper develops a star product formalism for Loop Quantum Cosmology, providing integral and differential representations that facilitate understanding of quantum dynamics and the semiclassical limit in LQC.

Contribution

It introduces a novel star product and star commutator for LQC, linking quantum and classical structures, and proposes a new approach to quantum evolution in the theory.

Findings

Constructed an integral representation of the star product for LQC.

Reproduced the holonomy-flux algebra and classical Poisson algebra.

Proposed a differential representation using finite differences.

Abstract

Guided by recent developments towards the implementation of the deformation quantization program within the Loop Quantum Cosmology (LQC) formalism, in this paper we address the introduction of both the integral and differential representation of the star product for LQC. To this end, we consider the Weyl quantization map for cylindrical functions defined on the Bohr compactification of the reals. The integral representation contains all of the common properties that characterize a star product which, in the case under study here, stands for a deformation of the usual pointwise product of cylindrical functions. Our construction also admits a direct comparison with the integral representation of the Moyal product which may be reproduced from our formulation by judiciously substituting the appropriate characters that identify such representation. Further, we introduce a suitable star commutator that correctly reproduces both the quantum representation of the holonomy-flux algebra for LQC and, in the proper limit, the holonomy-flux classical Poisson algebra emerging in the cosmological setup. Finally, we propose a natural way to obtain the quantum dynamical evolution in LQC in terms of this star commutator for cylindrical functions as well as a differential representation of the star product using discrete finite differences. We expect that our findings may contribute to a better understanding of certain issues arising within the LQC program, in particular, those related to the semiclassical limit and the dynamical evolution of quantum states.