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A version of the Cauchy-Schwarz inequality in operator theory is the following: for any two symmetric, positive definite matrices $A,B \in \mathbb{R}^{n \times n}$ and arbitrary $X \in \mathbb{R}^{n \times n}$ $$ \|AXB\| \leq \|A^2…

Functional Analysis · Mathematics 2016-08-18 Stefan Steinerberger

We investigate the question of whether the entropy and the Renyi entropies of the vacuum state reduced to a region of the space can be represented in terms of correlators in quantum field theory. In this case, the positivity relations for…

Quantum Physics · Physics 2014-11-20 H. Casini

Some of the important inequalities associated with quantum entropy are immediate algebraic consequences of the Hansen-Pedersen-Jensen inequality. A general argument is given in terms of the matrix perspective of an operator convex function.…

Mathematical Physics · Physics 2008-02-04 Edward G. Effros

We give some new refinements of Heinz inequality and an improvement of the reverse Young's inequality for scalars and we use them to establish new inequalities for operators and the Hilbert-Schmidt norm of matrices. We give a uniformly and…

Functional Analysis · Mathematics 2017-03-09 A. G. Ghazanfari , S. Malekinejad , S. Talebi

In the context of kernel optimization, we prove a result that yields new factorizations and realizations. Our initial context is that of general positive operator-valued kernels. We further present implications for Hilbert space-valued…

Operator Algebras · Mathematics 2024-10-14 Palle E. T. Jorgensen , James Tian

We study quantum equivalents of non-commutative operators in quantum mechanics. Any matrix "$B$" satisfying the non-commuting relation $[A,B]\neq 0$ with "$A$", can be used via $B^{-1} AB$ to reproduce eigenvalues of "$A$". This…

Quantum Physics · Physics 2023-01-24 Biswanath Rath

We revisit and extend results by Ueltschi [19] on the application of reflection positivity to loop models with $\theta \in \mathbb{N}_{\geq 2}$. By exploiting additional flexibility in the method, we prove the existence of long loops over a…

Mathematical Physics · Physics 2025-03-25 Volker Betz , Andreas Klippel , Julian Nauth

We extend some inequalities for normal matrices and positive linear maps related to the Russo-Dye theorem. The results cover the case of some positive linear maps on a von Neumann algebra mapping any nonzero operator to an unbounded…

Operator Algebras · Mathematics 2020-04-24 Jean-Christophe Bourin , Jingjing Shao

Operator systems connect operator algebra, free semialgebraic geometry and quantum information theory. In this work we generalize operator systems and many of their theorems. While positive semidefinite matrices form the underlying…

Operator Algebras · Mathematics 2025-12-12 Gemma De les Coves , Mirte van der Eyden , Tim Netzer

We describe the general structure of unbounded derivations in the quantum cylinder. We prove a noncommutative analog of reflection positivity for Laplace-type operators in a noncommutative cylinder following the ideas of Jaffe and Ritter…

Operator Algebras · Mathematics 2019-01-03 Slawomir Klimek , Matt McBride

The quantum rotor represents, after the harmonic oscillator, the next obvious quantum system to study the complementary pair of variables: the angular momentum and the unitary shift operator in angular momentum. Proper quantification of…

Quantum Physics · Physics 2024-08-13 Ladislav Mišta , Matouš Mišta , Zdeněk Hradil

The main pairs of leader operators of the quantum models of relativistic rotating oscillators in arbitrary dimensions are derived. To this end one exploits the fact that these models generate P\"{o}schl-Teller radial problems with…

General Relativity and Quantum Cosmology · Physics 2014-10-07 Ion I. Cotăescu , Ion I. Cotăescu , Nicolina Pop

Our main theorem is in the generality of the axioms of Hilbert space, and the theory of unbounded operators. Consider two Hilbert spaces such that their intersection contains a fixed vector space D. It is of interest to make a precise…

Functional Analysis · Mathematics 2017-01-19 Palle Jorgensen , Erin Pearse , Feng Tian

In this thesis, we present results from the investigation of two problems, one related to the phase transition of long-range Ising models and the other one associated with the characterization of equilibrium states in quantum spin systems.…

Mathematical Physics · Physics 2023-10-13 Lucas Affonso

Some new trace inequalities for operators in Hilbert spaces are provided. The superadditivity and monotonicity of some associated functionals are investigated and applications for power series of such operators are given. Some trace…

Functional Analysis · Mathematics 2014-09-24 Silvestru Sever Dragomir

We investigate matrices satisfying the Kreiss condition $$\|(zI-T)^{-1}\|\le\cfrac{K}{|z|-1}, \hspace{0.7 cm} |z|>1, $$ with $K$ lying arbitrarily close to $1.$ We provide lower bounds for the power growth of such matrices, which complement…

Functional Analysis · Mathematics 2026-03-12 Nikolaos Chalmoukis , Georgios Tsikalas , Dmitry Yakubovich

We consider some possible phenomenological implications of the extended uncertainty principle, which is believed to hold for quantum mechanics in de Sitter spacetime. The relative size of the corrections to the standard results is however…

High Energy Physics - Theory · Physics 2011-04-20 Subir Ghosh , Salvatore Mignemi

Operator matrices have played a significant role in studying Hilbert space operators. In this paper, we discuss further properties of operator matrices and present new estimates for the operator norms and numerical radii of such operators.…

Functional Analysis · Mathematics 2022-06-28 Fuad Kittaneh , Hamid Reza Moradi , Mohammad Sababheh

In this paper we construct a noncommutative space of ``pointed Drinfeld modules'' that generalizes to the case of function fields the noncommutative spaces of commensurability classes of Q-lattices. It extends the usual moduli spaces of…

Quantum Algebra · Mathematics 2007-05-23 Caterina Consani , Matilde Marcolli

We introduce the class of functions positively associated with a linear operator. We describe these classes for several integral operators including the $q$-cosine transform and the spherical Radon transform. We show that positively…

Functional Analysis · Mathematics 2025-06-30 Alexander Koldobsky