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The Bloch sphere is a familiar and useful geometrical picture of the dynamics of a single spin or two-level system's quantum evolution. The analogous geometrical picture for three-level systems is presented, with several applications. The…

Quantum Physics · Physics 2011-03-28 Sai Vinjanampathy , A. R. P. Rau

With a choice of boundary conditions for solutions of the Schr\"odinger equation, state vectors and density operators even for closed systems evolve asymmetrically in time. For open systems, standard quantum mechanics consequently predicts…

Quantum Physics · Physics 2010-05-25 P. W. Bryant

We present a comparative analysis of two different constructions of optimal-speed quantum Hamiltonian evolutions on the Bloch sphere. In the first approach (Mostafazadeh's approach), the evolution is specified by a traceless stationary…

Quantum Physics · Physics 2024-08-23 Leonardo Rossetti , Carlo Cafaro , Newshaw Bahreyni

Quantum fluctuations are fundamental in quantum technologies, affecting computing, sensing, cryptography, and thermodynamics. These include fluctuations in the variation of energy, charge, and other observables driven by interactions with…

Quantum Physics · Physics 2025-09-18 Thales Augusto Barbosa Pinto Silva , David Gelbwaser-Klimovsky

A two-sphere ("Bloch" or "Poincare") is familiar for describing the dynamics of a spin-1/2 particle or light polarization. Analogous objects are derived for unitary groups larger than SU(2) through an iterative procedure that constructs…

Quantum Physics · Physics 2009-11-13 D. Uskov , A. R. P. Rau

We explore the main processes involved in the evolution of general quantum systems by means of Diagrams of States, a novel method to graphically represent and analyze how quantum information is elaborated during computations performed by…

Quantum Physics · Physics 2009-12-02 Sara Felloni , Alberto Leporati , Giuliano Strini

We investigate monogamy of correlations and entropy inequalities in the Bloch representation. Here, both can be understood as direct relations between different correlation tensor elements and thus appear intimately related. To that end we…

Quantum Physics · Physics 2020-03-12 Paul Appel , Marcus Huber , Claude Klöckl

We demonstrate that among all quantum teleportation protocols giving rise to the same average fidelity, those with aligned Bloch vectors between input and output states exhibit the minimum average trace distance. This defines optimal…

Quantum Physics · Physics 2023-10-30 Fabricio Toscano , Diego G. Bussandri , Gustavo M. Bosyk , Ana P. Majtey , Mariela Portesi

In this paper we review some known results on the motion of Bloch Oscillators in the crystal momentum representation. We emphasize that the acceleration theorem, as usually stated by most of the authors, is incomplete, but in the case of…

Quantum Physics · Physics 2007-05-23 Vincenzo Grecchi , Andrea Sacchetti

We study the dynamics of electrons in crystalline solids in the presence of inhomogeneous external electric and magnetic fields. We present a manifestly gauge-invariant operator-based approach without relying on a semiclassical wavepacket…

Mesoscale and Nanoscale Physics · Physics 2025-03-17 Chen Xu , Andreas Haller , Suraj Hegde , Tobias Meng , Thomas L. Schmidt

The method of quantum tomography, which allows us to track with high accuracy the evolution of multilevel quantum systems (qudits) in Hilbert spaces of various dimensions is presented. The developed algorithms for quantum control are based…

Quantum Physics · Physics 2022-01-12 Yu. I. Bogdanov , N. A. Bogdanova , Yu. A. Kuznetsov , V. F. Lukichev

We present the method of describing an evolution in quantum cosmology in the framework of the reduced phase space quantization of loop cosmology. We apply our method to the flat Friedman-Robertson-Walker model coupled to a massless scalar…

General Relativity and Quantum Cosmology · Physics 2012-03-06 Jakub Mielczarek , Wlodzimierz Piechocki

The problem of finding a vacuum definition for a single quantum field in curved space-times is discussed under a new geometrical perspective. The phase space dynamics of the quantum field modes are mapped to curves in a 2-dimensional…

General Relativity and Quantum Cosmology · Physics 2023-04-12 Mariana Penna-Lima , Nelson Pinto-Neto , Sandro D. P. Vitenti

The Bloch equation is the fundamental dynamical model applicable to arbitrary two-level systems. Analytical solutions to date are incomplete for a number of reasons that motivate further investigation. The solution obtained here for the…

Quantum Physics · Physics 2017-04-05 Thomas E. Skinner

In quantum mechanics, geometry has been demonstrated as a useful tool for inferring non-classical behaviors and exotic properties of quantum systems. One standard approach to illustrate the geometry of quantum systems is to project the…

Starting from a geometric perspective, we derive a quantum speed limit for arbitrary open quantum evolution, which could be Markovian or non-Markovian, providing a fundamental bound on the time taken for the most general quantum dynamics.…

Quantum Physics · Physics 2019-08-07 Francesco Campaioli , Felix A. Pollock , Kavan Modi

This paper considers a generalization of the notion of quantum observables in ontological models of quantum mechanics. Within this framework it is possible to construct physical models where quantum noncommutativity can arise dynamically.…

Quantum Physics · Physics 2007-12-12 Tung Ten Yong

We celebrate this year hundred years of quantum mechanics but there is still no consensus regarding its interpretation and limitations. In this article we advocate the statistical contextual interpretation which is free of paradoxes. State…

Quantum Physics · Physics 2026-01-06 Marian Kupczynski

We discuss the structure of covariant equations, relating analytical properties of solutions to algebraic properties of the corresponding differential operator, specifically of its principal symbol. The principal symbol and its globality is…

General Relativity and Quantum Cosmology · Physics 2026-02-05 S. Coriasco , L. Fatibene , S. Garruto , A. Orizzonte

We present the quantum model of the asymptotic dynamics underlying the Belinski-Khalatnikov-Lifshitz (BKL) scenario. The symmetry of the physical phase space enables making use of the affine coherent states quantization. Our results show…

General Relativity and Quantum Cosmology · Physics 2019-02-20 Andrzej Góźdź , Włodzimierz Piechocki , Grzegorz Plewa