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We analyse the quantum evolution of a particle moving in a potential in interaction with an environment of harmonic oscillators in a thermal state, using the quantum state diffusion (QSD) picture of Gisin and Percival, in which one…

Quantum Physics · Physics 2011-07-19 Jonathan Halliwell , Andreas Zoupas

We consider graph states generated by the action of controlled phase shift operators on a separable state of a multi-qubit system. The case when all the qubits are initially prepared in arbitrary states is investigated. We obtain the…

Quantum Physics · Physics 2024-01-29 N. A. Susulovska

We investigate a quantum mechanical harmonic oscillator based on the extended Snyder model. This realization of the Snyder model is constructed as a quantum phase space generated by $D$ spatial coordinates and $D(D-1)/2$ tensorial degrees…

Quantum Physics · Physics 2022-08-23 S. Meljanac , S. Mignemi

The quantum operator $\hat{T}_3$, corresponding to the projection of the toroidal moment on the $z$ axis, admits several self-adjoint extensions, when defined on the whole $\mathbb{R}^3$ space. $\hat{T}_3$ commutes with $\hat{L}_3$ (the…

Quantum Physics · Physics 2021-01-18 Dragos-Victor Anghel , Amanda Teodora Preda

We analyze the size and evolution of quantum fluctuations of cosmologically relevant geometric observables, in the context of the effective relational cosmological dynamics of GFT models of quantum gravity. We consider the fluctuations of…

General Relativity and Quantum Cosmology · Physics 2021-09-23 Luca Marchetti , Daniele Oriti

Geometric measure of entanglement and geometric phase have recently been used to analyze quantum phase transition in the XY spin chain. We unify these two approaches by showing that the geometric entanglement and the geometric phase are…

Quantum Physics · Physics 2013-07-16 Vahid Azimi Mousolou , Carlo M. Canali , Erik Sjöqvist

The problem of defining time (or phase) operator for three-dimensional harmonic oscillator has been analyzed. A new formula for this operator has been derived. The results have been used to demonstrate a possibility of representing…

Quantum Physics · Physics 2009-11-07 Pavel Kundrat , Milos V. Lokajicek

Several conceptual aspects of quantum gravity are studied on the example of the homogeneous isotropic LQC model. In particular: $(i)$ The proper time of the co-moving observers is showed to be a quantum operator {and} a quantum spacetime…

General Relativity and Quantum Cosmology · Physics 2009-01-27 Wojciech Kaminski , Jerzy Lewandowski , Tomasz Pawlowski

Geometric phase is a promising element to induce high-fidelity and robust quantum operations due to its built-in noise-resilience feature. Unfortunately, its practical applications are usually circumscribed by requiring complex interactions…

Quantum Physics · Physics 2020-12-08 Tao Chen , Zheng-Yuan Xue

Based on local unitary operators acting on a n-dimensional Hilbert-space, we investigate selective and collective operator basis sets for N-particle quantum networks. Selective cluster operators are used to derive the properties of general…

Quantum Physics · Physics 2009-11-07 Alexander Otte , Guenter Mahler

Spontaneous symmetry breaking mechanism in quantum phase transitions manifests the existence of degenerate groundstates in broken symmetry phases. To detect such degenerate groundstates, we introduce a quantum fidelity as an overlap…

Statistical Mechanics · Physics 2013-09-11 Yao Heng Su , Bing-Quan Hu , Sheng-Hao Li , Sam Young Cho

The mathematical description of the quantum harmonic oscillator is essentially based on the Gaussian function. In the case of a quantum oscillator with finite-dimensional Hilbert space, the position space consists in a finite number of…

Mathematical Physics · Physics 2015-12-09 Nicolae Cotfas

We study bipartite unitary operators which stay invariant under the local actions of diagonal unitary and orthogonal groups. We investigate structural properties of these operators, arguing that the diagonal symmetry makes them suitable for…

Quantum Physics · Physics 2022-06-08 Satvik Singh , Ion Nechita

We formulate quantum field theory in triangulated spacetime using compositional quantum field theory and tensor network methods. We show that gravitational interactions emerge as a low-energy effective phenomenon in this framework. For…

High Energy Physics - Theory · Physics 2025-05-13 Matti Raasakka

The geometric properties of quantum states are crucial for understanding many physical phenomena in quantum mechanics, condensed matter physics, and optics. The central object describing these properties is the quantum geometric tensor,…

Mathematical Physics · Physics 2026-01-21 Marius A. Oancea , Thomas B. Mieling , Giandomenico Palumbo

We define quantum phase in terms of inverses of annihilation and creation operators. We show that like Susskind - Glogower phase operators, the measured phase operators and the unitary phase operators can be defined in terms of the inverse…

Quantum Physics · Physics 2008-03-17 G. M. Saxena

We construct a quantum gate entangler based on selective phase rotation transform. In particular, we established a relation between quantum integral transform and quantum gates entangler in terms of universal controlled gates for…

Quantum Physics · Physics 2009-12-21 Hoshang Heydari

The geometric phases for standard coherent states which are widely used in quantum optics have attracted a large amount of attention. Nevertheless, few physicists consider about the counterparts of non-linear coherent states, which are…

Quantum Physics · Physics 2011-05-24 Da-Bao Yang , Ying Chen , Fu-Lin Zhang , Jing-Ling Chen

The Transformer model, renowned for its powerful attention mechanism, has achieved state-of-the-art performance in various artificial intelligence tasks but faces challenges such as high computational cost and memory usage. Researchers are…

Quantum Physics · Physics 2026-03-24 Yuichi Kamata , Quoc Hoan Tran , Yasuhiro Endo , Hirotaka Oshima

In the Quantum-Train (QT) framework, mapping quantum state measurements to classical neural network weights is a critical challenge that affects the scalability and efficiency of hybrid quantum-classical models. The traditional QT framework…

Quantum Physics · Physics 2024-09-12 Chen-Yu Liu , Chu-Hsuan Abraham Lin , Kuan-Cheng Chen