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Numerical Evolution Of Squeezed And Non-Gaussian States In Loop Quantum Cosmology, Peter Diener, Brajesh Gupt, Miguel Megevand, Parampreet Singh
Numerical Evolution Of Squeezed And Non-Gaussian States In Loop Quantum Cosmology, Peter Diener, Brajesh Gupt, Miguel Megevand, Parampreet Singh
Faculty Publications
In recent years, numerical simulations with Gaussian initial states have demonstrated the existence of a quantum bounce in loop quantum cosmology in various models. A key issue pertaining to the robustness of the bounce and the associated physics is to understand the quantum evolution for more general initial states, which may depart significantly from Gaussianity and may have no well defined peakedness properties. The analysis of such states, including squeezed and highly non-Gaussian states, has been computationally challenging until now. In this paper, we overcome these challenges by using the Chimera scheme for the spatially flat, homogeneous and isotropic model …
Numerical Simulations Of A Loop Quantum Cosmos: Robustness Of The Quantum Bounce And The Validity Of Effective Dynamics, Peter Diener, Brajesh Gupt, Parampreet Singh
Numerical Simulations Of A Loop Quantum Cosmos: Robustness Of The Quantum Bounce And The Validity Of Effective Dynamics, Peter Diener, Brajesh Gupt, Parampreet Singh
Faculty Publications
A key result of isotropic loop quantum cosmology is the existence of a quantum bounce which occurs when the energy density of the matter field approaches a universal maximum close to the Planck density. Though the bounce has been exhibited in various matter models, due to severe computational challenges, some important questions have so far remained unaddressed. These include the demonstration of the bounce for widely spread states, its detailed properties for the states when matter field probes regions close to the Planck volume and the reliability of the continuum effective spacetime description in general. In this manuscript we rigorously …
Quantization Ambiguities And Bounds On Geometric Scalars In Anisotropic Loop Quantum Cosmology, Parampreet Singh, Edward Wilson-Ewing
Quantization Ambiguities And Bounds On Geometric Scalars In Anisotropic Loop Quantum Cosmology, Parampreet Singh, Edward Wilson-Ewing
Faculty Publications
We study quantization ambiguities in loop quantum cosmology that arise for space-times with non-zero spatial curvature and anisotropies. Motivated by lessons from different possible loop quantizations of the closed Friedmann-Lemaître-Robertson-Walker cosmology, we find that using open holonomies of the extrinsic curvature, which due to gauge-fixing can be treated as a connection, leads to the same quantum geometry effects that are found in spatially flat cosmologies. More specifically, in contrast to the quantization based on open holonomies of the Ashtekar-Barbero connection, the expansion and shear scalars in the effective theories of the Bianchi type II and Bianchi type IX models have …
Chimera: A Hybrid Approach To Numerical Loop Quantum Cosmology, Peter Diener, Brajesh Gupt, Parampreet Singh
Chimera: A Hybrid Approach To Numerical Loop Quantum Cosmology, Peter Diener, Brajesh Gupt, Parampreet Singh
Faculty Publications
The existence of a quantum bounce in isotropic spacetimes is a key result in loop quantum cosmology (LQC), which has been demonstrated to arise in all the models studied so far. In most of the models, the bounce has been studied using numerical simulations involving states which are sharply peaked and which bounce at volumes much larger than the Planck volume. An important issue is to confirm the existence of the bounce for states which have a wide spread, or which bounce closer to the Planck volume. Numerical simulations with such states demand large computational domains, making them very expensive …
Some Numerical And Phenomenological Studies In Loop Quantum Cosmology, Brajesh Kumar Gupt
Some Numerical And Phenomenological Studies In Loop Quantum Cosmology, Brajesh Kumar Gupt
LSU Doctoral Dissertations
A key feature of the singularity resolution in loop quantum cosmology (LQC) is the occurrence of the quantum bounce when the spacetime curvature becomes comparable to the Planck scale. The presence of quantum bounce greatly modifies the dynamics of the early universe and can have important implications for observational signatures. Although the quantum bounce has been previously studied via numerical methods for initial conditions that correspond to large macroscopic universes at late times, a detailed study of the robustness of the quantum bounce for a generic class of initial condition has so far been missing due to severe computational challenges. …