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An early result of algebraic quantum field theory is that the algebra of any subregion in a QFT is a von Neumann factor of type III$_1$, in which entropy cannot be well-defined because such algebras do not admit a trace or density states.…

High Energy Physics - Theory · Physics 2024-05-02 Shadi Ali Ahmad , Ro Jefferson

We give a complete answer to the questions of factoriality, type classification and fullness for arbitrary free product von Neumann algebras.

Operator Algebras · Mathematics 2019-05-21 Yoshimichi Ueda

If $G$ is a compact group, continuous normalized positive definite functions are in one-to-one correspondence with unital quantum channels acting as Fourier multipliers on the group von Neumann algebra $\mathrm{VN}(G)$. We study the convex…

Operator Algebras · Mathematics 2026-03-04 Cédric Arhancet , Lei Li

We consider amalgamated free product II$_1$ factors $M = M_1 *_B M_2 *_B ...$ and use ``deformation/rigidity'' and ``intertwining'' techniques to prove that any relatively rigid von Neumann subalgebra $Q\subset M$ can be intertwined into…

Operator Algebras · Mathematics 2007-12-27 A. Ioana , J. Peterson , S. Popa

The factorization of the universal R-matrix corresponding to so called Drinfeld Hopf structure is described on the example of quantum affine algebra $U_q(\hat{sl}_2)$. As a result of factorization procedure we deduce certain differential…

Quantum Algebra · Mathematics 2009-10-31 J. Ding , S. Khoroshkin , S. Pakuliak

We prove that the von Neumann algebras generated by $n$ $q$-Gaussian elements, are factors for $n\ge 2$.

Functional Analysis · Mathematics 2010-04-22 Eric Ricard

We show that a locally compact group has open unimodular part if and only if the Plancherel weight on its group von Neumann algebra is almost periodic. We call such groups almost unimodular. The almost periodicity of the Plancherel weight…

Operator Algebras · Mathematics 2025-11-04 Aldo Garcia Guinto , Brent Nelson

We consider commuting squares of finite dimensional von Neumann algebras having the algebra of complex numbers in the lower left corner. Examples include the vertex models, the spin models (in the sense of subfactor theory) and the…

Operator Algebras · Mathematics 2007-05-23 Teodor Banica

In this work we give a generalization of matched pairs of (finite) groups to describe a general class of depth two inclusions of factor von Neumann algebras and the C*-quantum groupoids associated with, using double groupoids.

Operator Algebras · Mathematics 2007-05-23 Jean-Michel Vallin

We use filtrations of the Grassmannian model to produce explicit algebraic formulae for all harmonic maps of finite uniton number from a Riemann surface, and so all harmonic maps from the 2-sphere, to the unitary group for a general class…

Differential Geometry · Mathematics 2010-08-12 Martin Svensson , John C. Wood

In this paper we study conditions under which, for an inclusion of finite von Neumann algebras $N \subseteq M$, we have the reduced amalgamated free product $\ast_N M$ is embeddable into $(R \bar{\otimes} N_1)^\omega$ for some other finite…

Operator Algebras · Mathematics 2021-12-07 Weichen Gao , Marius Junge , Weichen Gao

We compute the conjugate system of twisted Araki-Woods von Neumann algebras $ \mathcal{L}_T(H) $ for a compatible braided crossing symmetric twist $T$ on a finite dimensional Hilbert space $ \mathcal{H} $ with norm $ \|T\| <1$. This implies…

Operator Algebras · Mathematics 2023-08-01 Zhiyuan Yang

We investigate criteria for von-Neumann finiteness and reversibility in some classes of non-associative algebras. We show that all finite-dimensional alternative algebras, as well as all algebras obtained from the real numbers via the…

Rings and Algebras · Mathematics 2020-09-02 Erik Darpö , Patrik Nystedt

Let $M$ be a II$_1$ factor with a von Neumann subalgebra $Q\subset M$ that has infinite index under any projection in $Q'\cap M$ (e.g., $Q$ abelian; or $Q$ an irreducible subfactor with infinite Jones index). We prove that given any…

Operator Algebras · Mathematics 2018-10-22 Sorin Popa

Let $C$ be a symmetrizable generalized Cartan Matrix, and $q$ an indeterminate. ${\fg}(C)$ is the Kac-Moody Lie algebra and $U=U_q({\fg}(C))$ the associated quantum enveloping algebra over $ k={\Bbb Q}(q)$. The quantum function algebra…

Quantum Algebra · Mathematics 2007-05-23 Bharath Narayanan

Consider the free orthogonal quantum groups $O_N^+(F)$ and free unitary quantum groups $U_N^+(F)$ with $N \geq 3$. In the case $F = {\rm id}_N$ it was proved both by Isono and Fima-Vergnioux that the associated finite von Neumann algebra…

Operator Algebras · Mathematics 2020-10-21 Martijn Caspers

We introduce notation Q(1) * ... * Q(n) * L(F_r)$ for von Neumann algebra II_1 factors where $r$ is allowed to be negative. This notation is defined by rescalings of free products of II_1 factors, and is proved to be consistent with known…

Operator Algebras · Mathematics 2007-05-23 Ken Dykema , Florin Radulescu

In this short note, we construct an exotic example of a locally compact group $G$ with a Borel $2$-cocycle $\omega$ such that the non-twisted group von Neumann algebra $L(G)$ is a factor, while the twisted group von Neumann algebra…

Operator Algebras · Mathematics 2025-08-13 Stefaan Vaes

The zero modes of the chiral SU(n) WZNW model give rise to an intertwining quantum matrix algebra A generated by an n x n matrix a=(a^i_\alpha) (with noncommuting entries) and by rational functions of n commuting elements q^{p_i}. We study…

High Energy Physics - Theory · Physics 2008-11-26 P. Furlan , L. K. Hadjiivanov , A. P. Isaev , O. V. Ogievetsky , P. N. Pyatov , I. T. Todorov

We initiate a study of linear maps on $M_n(\mathbb{C})$ that have the property that they factor through a tracial von Neumann algebra $(\mathcal{A,\tau})$ via operators $Z\in M_n(\mathcal{A})$ whose entries consist of positive elements from…

Operator Algebras · Mathematics 2021-09-06 Jeremy Levick , Mizanur Rahaman