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200 papers

Utilizing the previously established general formalism for quantum symmetry reduction in the framework of loop quantum gravity the spectrum of the area operator acting on spherically symmetric states in 4 dimensional pure gravity is…

High Energy Physics - Theory · Physics 2009-10-31 M. Bojowald , H. A. Kastrup

Geometric quantum mechanics aims to express the physical properties of quantum systems in terms of geometrical features preferentially selected in the space of pure states. Geometric characterisations are given here for systems of one, two,…

Quantum Physics · Physics 2007-06-13 Dorje C. Brody , Anna C. T. Gustavsson , Lane P. Hughston

The suggested operator manifold formalism enables to develop an approach to the unification of the geometry and the field theory. We also elaborate the formalism of operator multimanifold yielding the multiworld geometry involving the…

High Energy Physics - Theory · Physics 2007-05-23 G. T. Ter-Kazarian

Spin networks, essentially labeled graphs, are ``good quantum numbers'' for the quantum theory of geometry. These structures encompass a diverse range of techniques which may be used in the quantum mechanics of finite dimensional systems,…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Seth A. Major

Geometric quantization is an attempt at using the differential-geometric ingredients of classical phase spaces regarded as symplectic manifolds in order to define a corresponding quantum theory. Generally, the process of geometric…

Mathematical Physics · Physics 2018-01-09 Andrea Carosso

Quantum estimation of the operators of a system is investigated by analyzing its Liouville space of operators. In this way it is possible to easily derive some general characterization for the sets of observables (i.e. the possible quorums)…

Quantum Physics · Physics 2009-11-06 G. M. D'Ariano , L. Maccone , M. G. A. Paris

In our previous works, we introduced, for each (super)manifold, a commutative algebra of densities. It is endowed with a natural invariant scalar product. In this paper, we study geometry of differential operators of second order on this…

Differential Geometry · Mathematics 2017-07-25 H. M. Khudaverdian , Th. Th. Voronov

All elementary particles in nature can be classified as fermions with half-integer spin and bosons with integer spin. Within quantum electrodynamics (QED), even though the spin of the Dirac particle is well defined, there exist open…

Quantum Physics · Physics 2022-06-01 Li-Ping Yang , Farhad. Khosravi , Zubin Jacob

The phenomenology for the deep spatial geometry of loop quantum gravity is discussed. In the context of a simple model of an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Seth A. Major

Geometrical structures of quantum mechanics provide us with new insightful results about the nature of quantum theory. In this work we consider mixed quantum states represented by finite rank density operators. We review our geometrical…

Quantum Physics · Physics 2015-06-23 Hoshang Heydari , Ole Andersson

The Pryce (e) spin and position operators of the quantum theory of Dirac's free field were re-defined and studied recently with the help of a new spin symmetry and suitable spectral representations [I. I. Cot\u aescu, Eur. Phys. J. C (2022)…

Quantum Physics · Physics 2024-11-04 Ion I. Cotaescu

Spinors have played an essential but enigmatic role in modern physics since their discovery. Now that quantum-gravitational theories have started to become available, the inclusion of a description of spin in the development is natural and…

Mathematical Physics · Physics 2007-05-23 Daniel C. Galehouse

We consider the geometry of second order linear operators acting on the commutative algebra of densities on a (super)manifold introduced in our previous work. In the conventional language, operators on the algebra of densities correspond to…

Mathematical Physics · Physics 2014-10-16 H. M. Khudaverdian , Th. Th. Voronov

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

Results that illuminate the physical interpretation of states of nonperturbative quantum gravity are obtained using the recently introduced loop variables. It is shown that: i) While local operators such as the metric at a point may not be…

High Energy Physics - Theory · Physics 2011-04-20 Abhay Ashtekar , Carlo Rovelli , Lee Smolin

The moment operators of a semispectral measure having the structure of the convolution of a positive measure and a semispectral measure are studied, with paying attention to the natural domains of these unbounded operators. The results are…

Quantum Physics · Physics 2009-11-13 Jukka Kiukas , Pekka Lahti , Kari Ylinen

The kinematical setting of spherically symmetric quantum geometry, derived from the full theory of loop quantum gravity, is developed. This extends previous studies of homogeneous models to inhomogeneous ones where interesting field theory…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Martin Bojowald

The space of states and operators for a large class of background independent theories of quantum spacetime dynamics is defined. The SU(2) spin networks of quantum general relativity are replaced by labelled compact two-dimensional…

General Relativity and Quantum Cosmology · Physics 2016-08-25 Fotini Markopoulou , Lee Smolin

We develop the first steps towards an analysis of geometry on the quantum spacetime proposed in [1]. The homogeneous elements of the universal differential algebra are naturally identified with operators living in tensor powers of Quantum…

High Energy Physics - Theory · Physics 2015-03-17 Dorothea Bahns , Sergio Doplicher , Klaus Fredenhagen , Gherardo Piacitelli

We define and discuss various quantum operators that describe the geometry of spacetime in quantum general relativity. These are obtained by combining the Null-Surface Formulation of general relativity, recently developed, with asymptotic…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Simonetta Frittelli , Carlos N. Kozameh , Ezra T. Newman , Carlo Rovelli , Ranjeet S. Tate