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We describe how to construct and compute unambiguously path integrals for particles moving in a curved space, and how these path integrals can be used to calculate Feynman graphs and effective actions for various quantum field theories with…

High Energy Physics - Theory · Physics 2007-05-23 Fiorenzo Bastianelli

The definition of physical states is the main technical issue of canonical approaches towards Quantum Gravity. In this work, we outline how those states can be found in Einstein-Cartan theory via a continuum limit and they are given by…

General Relativity and Quantum Cosmology · Physics 2016-05-06 Francesco Cianfrani

An adapted representation of quantum mechanics sheds new light on the relationship between quantum states and classical states. In this approach the space of quantum states splits into a product of the state space of classical mechanics and…

High Energy Physics - Theory · Physics 2021-04-14 Christoph Nölle

We construct a state in the loop quantum gravity theory with zero cosmological constant, which should correspond to the flat spacetime vacuum solution. This is done by defining the loop transform coefficients of a flat connection…

General Relativity and Quantum Cosmology · Physics 2009-01-16 A. Mikovic

A new routine is proposed to relate Loop Quant Cosmology (LQC) to Loop Quantum Gravity (LQG) from the perspective of effective dynamics. We derive the big-bang singularity resolution and big bounce from the first principle of full canonical…

General Relativity and Quantum Cosmology · Physics 2020-02-12 Muxin Han , Hongguang Liu

We define a (semi-classical) path integral for gravity with Neumann boundary conditions in $D$ dimensions, and show how to relate this new partition function to the usual picture of Euclidean quantum gravity. We also write down the action…

High Energy Physics - Theory · Physics 2017-03-01 Chethan Krishnan , K. V. Pavan Kumar , Avinash Raju

Quantum versions of cylindric phase space, like for the motion of a particle on the circle, are obtained through different families of coherent states. The latter are built from various probability distributions of the action variable. The…

Quantum Physics · Physics 2015-06-03 I. Aremua , J. P. Gazeau , M. N. Hounkonnou

It is straightforward to give a sum-over-paths expression for the transition amplitudes of a quantum circuit as long as the gates in the circuit are balanced, where to be balanced is to have all nonzero transition amplitudes of equal…

Quantum Physics · Physics 2017-08-15 Mark D. Penney , Dax Enshan Koh , Robert W. Spekkens

The path-integral approach to cosmology consists in the computation of transition amplitudes between states of the quantum geometry of the universe. In the past, the concrete computation of these transitions amplitudes has been performed in…

General Relativity and Quantum Cosmology · Physics 2012-05-22 Francesca Vidotto

A discrete path integral formalism is used to obtain the transition amplitude between 'sources' (slits and detector) in the twin-slit experiment of quantum mechanics. This method explicates the normally tacit construct of dynamic entities…

Quantum Physics · Physics 2007-12-12 W. M. Stuckey

As part of a wider study of coherent states in (loop) quantum gravity, we introduce a modification to the standard construction, based on the recently introduced (non-commutative) flux representation. The resulting quantum states have some…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Daniele Oriti , Roberto Pereira , Lorenzo Sindoni

We compute the transition amplitude between coherent quantum-states of geometry peaked on homogeneous isotropic metrics. We use the holomorphic representations of loop quantum gravity and the Kaminski-Kisielowski-Lewandowski generalization…

General Relativity and Quantum Cosmology · Physics 2010-10-27 Eugenio Bianchi , Carlo Rovelli , Francesca Vidotto

An extension of the classical action principle obtained in the framework of the gauge transformations, is used to describe the motion of a particle. This extension assigns many, but not all, paths to a particle. Properties of the particle…

Quantum Physics · Physics 2007-05-23 S. R. Vatsya

In canonical quantum gravity, when space is a compact manifold with boundary there is a Hamiltonian given by an integral over the boundary. Here we compute the action of this `boundary Hamiltonian' on observables corresponding to open…

General Relativity and Quantum Cosmology · Physics 2009-10-28 John Baez , Javier P. Muniain , Dardo Piriz

Non-Abelian Gauss law is interpreted in terms of area bits described in a local frame which fit together into closed surfaces and the Non-Abelian Stokes law in terms of length bits described in a local frame which fit together into closed…

General Relativity and Quantum Cosmology · Physics 2007-05-23 H. S. Sharatchandra , H. Gopalkrishna Gadiyar

We present a general framework for the production of squeezed quantum states of the gravitational field in linearized quantum gravity. Time-dependent couplings in the quadratic part of the action generically produce squeezed states from the…

General Relativity and Quantum Cosmology · Physics 2025-12-24 Arunima Das , Maulik Parikh , Frank Wilczek , Raphaela Wutte

The manifold of pure quantum states is a complex projective space endowed with the unitary-invariant geometry of Fubini and Study. According to the principles of geometric quantum mechanics, the detailed physical characteristics of a given…

Quantum Physics · Physics 2015-06-26 Dorje C. Brody , Lane P. Hughston

We use an integral quantization model based on the Heisenberg-Weyl group to describe the motion of a spinless particle in the Minkowski background spacetime. This work is a sequel to a previous paper, devoted to mathematical aspects of our…

General Relativity and Quantum Cosmology · Physics 2025-09-23 Adam Cieślik , Andrzej Góźdź , Patryk Mach , Aleksandra Pȩdrak , Włodzimierz Piechocki

The gravity action on the piecewise flat Riemannian manifold is formulated using the discrete set of the nondegenerate 4$\times$4 matrices on the 3-simplices as some connection type variables. These variables are the discrete counterpart of…

General Relativity and Quantum Cosmology · Physics 2016-12-21 V. M. Khatsymovsky

We propose path integral description for quantum mechanical systems on compact graphs consisting of N segments of the same length. Provided the bulk Hamiltonian is segment-independent, scale-invariant boundary conditions given by…

High Energy Physics - Theory · Physics 2012-06-06 Satoshi Ohya