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When initially introduced, a Hamiltonian that realises perfect transfer of a quantum state was found to be analogous to an x-rotation of a large spin. In this paper we extend the analogy further to demonstrate geometric effects by…

Quantum Physics · Physics 2007-05-23 Alastair Kay , Marie Ericsson

We investigate graphs that can be disconnected into small components by removing a vanishingly small fraction of their vertices. We show that when a quantum network is described by such a graph, the network is efficiently controllable, in…

Quantum Physics · Physics 2017-07-05 Can Gokler , Seth Lloyd , Peter Shor , Kevin Thompson

Within the framework of Quantum Reduced Loop Gravity we quantize the Hamiltonian for a gauge vector field. The regularization can be performed using tools analogous to the ones adopted in full Loop Quantum Gravity, while the matrix elements…

General Relativity and Quantum Cosmology · Physics 2017-06-07 Jakub Bilski , Emanuele Alesci , Francesco Cianfrani , Pietro Donà , Antonino Marciano

Two desireable properties of a quantum dynamics for Loop Quantum Gravity (LQG) are that its generators provide an anomaly free representation of the classical constraint algebra and that physical states which lie in the kernel of these…

General Relativity and Quantum Cosmology · Physics 2019-09-25 Madhavan Varadarajan

In this work, we propose novel families of positional encodings tailored to graph neural networks obtained with quantum computers. These encodings leverage the long-range correlations inherent in quantum systems that arise from mapping the…

An improved Hamiltonian constraint operator is introduced in loop quantum cosmology. Quantum dynamics of the spatially flat, isotropic model with a massless scalar field is then studied in detail using analytical and numerical methods. The…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Abhay Ashtekar , Tomasz Pawlowski , Parampreet Singh

In a companion paper we introduced a kinematical arena for the discussion of the constraints of canonical quantum gravity in the spin network representation based on Vassiliev invariants. In this paper we introduce the Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Cayetano Di Bartolo , Rodolfo Gambini , Jorge Griego , Jorge Pullin

Loop Quantum Gravity (LQG) is one of the leading approaches to unify quantum physics and General Relativity (GR). The Hilbert space of LQG is spanned by spin-networks which describe the local geometry of quantum space-time. Simulation of…

General Relativity and Quantum Cosmology · Physics 2021-12-21 Swapnil Nitin Shah

It is well known that Einstein's equations assume a simple polynomial form in the Hamiltonian framework based on a Yang-Mills phase space. We re-examine the gravitational dynamics in this framework and show that {\em time} evolution of the…

General Relativity and Quantum Cosmology · Physics 2021-01-14 Abhay Ashtekar , Madhavan Varadarajan

In loop quantum cosmology, one has to make a choice of SU(2) irreducible representation in which to compute holonomies and regularize the curvature of the connection. The systematic choice made in the literature is to work in the…

General Relativity and Quantum Cosmology · Physics 2017-04-26 Jibril Ben Achour , Suddhasattwa Brahma , Marc Geiller

Quantum graphity is a background independent model for emergent locality, spatial geometry and matter. The states of the system correspond to dynamical graphs on N vertices. At high energy, the graph describing the system is highly…

High Energy Physics - Theory · Physics 2008-11-26 Tomasz Konopka , Fotini Markopoulou , Simone Severini

We address the study of controllability of a closed quantum system whose dynamical Lie algebra is generated by adjacency matrices of graphs. We characterize a large family of graphs that renders a system controllable. The key property is a…

Quantum Physics · Physics 2012-01-10 Chris Godsil , Simone Severini

An anomaly-free operator corresponding to the Wheeler-DeWitt constraint of Lorentzian, four-dimensional, canonical, non-perturbative vacuum gravity is constructed in the continuum. This operator is entirely free of factor ordering…

General Relativity and Quantum Cosmology · Physics 2008-11-26 T. Thiemann

We consider the statics and dynamics of distinguishable spin-1/2 systems on an arbitrary graph G with N vertices. In particular, we consider systems of quantum spins evolving according to one of two hamiltonians: (i) the XY hamiltonian…

Quantum Physics · Physics 2007-05-23 Tobias J. Osborne

Quantum random walks represent a powerful tool for the implementation of various quantum algorithms. We consider a convolution problem for the graphs which provide quantum and classical random walks. We suggest a new method for lattices and…

Quantum Physics · Physics 2025-07-23 Roman Abramov , Leonid Fedichkin , Dmitry Tsarev , Alexander Alodjants

I describe a possible perspective on the current state of loop quantum gravity, at the light of the developments of the last years. I point out that a theory is now available, having a well-defined background-independent kinematics and a…

General Relativity and Quantum Cosmology · Physics 2011-05-25 Carlo Rovelli

Spherically symmetric models of loop quantum gravity have been studied recently by different methods that aim to deal with structure functions in the usual constraint algebra of gravitational systems. As noticed by Gambini and Pullin, a…

General Relativity and Quantum Cosmology · Physics 2015-09-09 Martin Bojowald , Suddhasattwa Brahma , Juan D. Reyes

We introduce a new regularization scheme for Quantum Cosmology in Loop Quantum Gravity (LQG) using the tools of Quantum Reduced Loop Gravity (QRLG). It is obtained considering density matrices for superposition of graphs based on…

General Relativity and Quantum Cosmology · Physics 2019-01-23 Emanuele Alesci , Gioele Botta , Gabriele V. Stagno

In this article, we review the use of numerical techniques to obtain solutions for the quantum Hamiltonian constraint in loop quantum cosmology (LQC). First, we summarize the basic features of LQC, and describe features of the constraint…

General Relativity and Quantum Cosmology · Physics 2012-01-04 David Brizuela , Daniel Cartin , Gaurav Khanna

We review some approaches to the Hamiltonian dynamics of (loop) quantum gravity, the main issues being the regularization of the Hamiltonian and the continuum limit. First, Thiemann's definition of the quantum Hamiltonian is presented, and…

General Relativity and Quantum Cosmology · Physics 2012-03-08 Valentin Bonzom , Alok Laddha
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