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We investigate dynamics of semi-quantal spin systems in which quantum bits are attached to classically and possibly stochastically moving classical particles. The interaction between the quantum bits takes place when the respective…

Quantum Physics · Physics 2009-11-13 Matyas Koniorczyk , Arpad Varga , Peter Rapcan , Vladimir Buzek

We study the compatibility of the quantum homogeneitiy and isotropy hypothesis (QHIH), proposed by Ashtekar and Gupt to restrict the choice of vacuum state for the cosmological perturbations in Loop Quantum Cosmology (LQC), with the…

General Relativity and Quantum Cosmology · Physics 2021-12-30 Beatriz Elizaga Navascués , Guillermo A. Mena Marugán , Santiago Prado

The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a…

Quantum Physics · Physics 2015-05-18 Evgeni A. Solov'ev

Semiclassical techniques have proven to be a very powerful method to extract physical effects from different quantum theories. Therefore, it is expected that in the near future they will play a very prominent role in the context of quantum…

General Relativity and Quantum Cosmology · Physics 2014-12-17 David Brizuela

The so-called classical limit of quantum mechanics is generally studied in terms of the decoherence of the state operator that characterizes a system. This is not the only possible approach to decoherence. In previous works we have…

Quantum Physics · Physics 2015-05-18 Sebastian Fortin , Leonardo Vanni

We describe different strategies for using a semi-classical controller to engineer quantum Hamiltonians to solve control problems such as quantum state or process engineering or optimization of observables.

Quantum Physics · Physics 2009-10-01 Sonia G Schirmer

The entropy of apparent horizons is derived using coherent states or semiclassical states in quantum gravity. The leading term is proportional to area for large horizons, and the correction terms differ according to the details of the graph…

General Relativity and Quantum Cosmology · Physics 2009-11-13 Arundhati Dasgupta

Coherent states provide a natural connection of quantum systems to their classical limit and are employed in various fields of physics. Here we derive general systematic expansions, with respect to quantum parameters, of expectation values…

Quantum Physics · Physics 2015-08-13 John Schliemann

In a wide range of quantum gravity theories, quasiclassical geometries, which are solutions to the Einstein field equations approximately, are described by "coherent states." Here we propose a Hamiltonian formalism for gravitational…

General Relativity and Quantum Cosmology · Physics 2025-12-01 Sijia Wang , Achintya Sajeendran , Dong-han Yeom , Robert B. Mann , Joshua Foo

The coherent states for a set of quadratic Hamiltonians in the trap regime are constructed. A matrix technique which allows to identify directly the creation and annihilation operators will be presented. Then, the coherent states as…

Quantum Physics · Physics 2011-09-16 Alonso Contreras-Astorga , David J Fernandez C , Mercedes Velazquez

Semiclassical mechanics of systems with first-class constraints is developed. Starting from the quantum theory, one investigates such objects as semiclassical states and observables, semiclassical inner product, semiclassical gauge…

High Energy Physics - Theory · Physics 2007-05-23 Oleg Shvedov

We re-examine the semiclassical approximation to quantum gravity in the canonical formulation, focusing on the definition of a quasiclassical state for the gravitational field. It is shown that a state with classical correlations must be a…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Gilad Lifschytz , Samir D. Mathur , Miguel E. Ortiz

We study the Hydrogen atom as a quantum mechanical system with a Coulomb like potential, with a semiclassical approach based on an effective description of quantum mechanics. This treatment allows us to describe the quantum state of the…

Quantum Physics · Physics 2012-03-23 Guillermo Chacón-Acosta , Héctor H. Hernández

In this paper we address the meaning of states in loop quantum cosmology (LQC), in the context of loop quantum gravity. First, we introduce a rigorous formulation of an embedding proposed by Bojowald and Kastrup, of LQC states into loop…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Jonathan Engle

Unique set of coherent states for the anharmonic oscillator is obtained by requiring i. under the quantum mechanical time evolution a coherent state evolves into another, governed by trajectory in the classical phase space (of a related…

Quantum Physics · Physics 2007-05-23 H. S. Sharatchandra

This paper discusses fully coherent quantum feedback control, in which the sensors, controller, and actuators are quantum systems and interact coherently with the system to be controlled: as a result, the entire feedback loop is coherent.…

Quantum Physics · Physics 2007-05-23 Seth Lloyd

The continuum and semiclassical limits of isotropic, spatially flat loop quantum cosmology are discussed, with an emphasis on the role played by the Barbero-Immirzi parameter \gamma in controlling space-time discreteness. In this way,…

General Relativity and Quantum Cosmology · Physics 2010-05-28 Martin Bojowald

Within the framework of loop quantum cosmology, there exists a semi-classical regime where spacetime may be approximated in terms of a continuous manifold, but where the standard Friedmann equations of classical Einstein gravity receive…

General Relativity and Quantum Cosmology · Physics 2009-11-10 James E. Lidsey

We construct the quantum group $GL_q(2)$ as the semi-infinite cohomology of the tensor product of two braided vertex operator algebras based on the algebra $W_2$ with complementary central charges $c+\bar{c}=28$. The conformal field theory…

Representation Theory · Mathematics 2014-03-11 Igor B. Frenkel , Anton M. Zeitlin

We compute the two-point correlation function of the area operator for semiclassical states of loop quantum gravity in the limit of large spins. The cases of intrinsic and extrinsic coherent states are considered, along with a new class of…

General Relativity and Quantum Cosmology · Physics 2025-10-29 Filipe H. C. Menezes , Nelson Yokomizo