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We present examples of equivariant noncommutative Lorentzian spectral geometries. The equivariance with respect to a compact isometry group (or quantum group) allows to construct the algebraic data of a version of spectral triple geometry…

Mathematical Physics · Physics 2007-05-23 Mario Paschke , Andrzej Sitarz

It often goes unnoticed that, even for a finite number of degrees of freedom, the canonical commutation relations have many inequivalent irreducible unitary representations; the free particle and a particle in a box provide examples that…

Quantum Physics · Physics 2012-01-25 R. N. Sen

We formulate a quantum group analogue of the group of orinetation-preserving Riemannian isometries of a compact Riemannian spin manifold, more generally, of a (possibly $R$-twisted in the sense of a paper of one of the authors, and of…

Quantum Algebra · Mathematics 2008-11-19 Jyotishman Bhowmick , Debashish Goswami

Covariant first order differential calculus over quantum complex Grassmann manifolds is considered. It is shown by a Pusz-Woronowicz type argument that under restriction to calculi close to classical Kaehler differentials there exist…

Quantum Algebra · Mathematics 2016-09-07 Stefan Kolb

We investigate the equivalence of quantum mixed states under local unitary transformations. For a class of rank-two mixed states, a sufficient and necessary condition of local equivalence is obtained by giving a complete set of invariants…

Quantum Physics · Physics 2007-11-09 Sergio Albeverio , Shao-Ming Fei , Debashish Goswami

Convolution semigroups of states on a quantum group form the natural noncommutative analogue of convolution semigroups of probability measures on a locally compact group. Here we initiate a theory of weakly continuous convolution semigroups…

Operator Algebras · Mathematics 2009-10-28 J. Martin Lindsay , Adam Skalski

Consider a locally compact group $G=Q\ltimes V$ such that $V$ is abelian and the action of $Q$ on the dual abelian group $\hat V$ has a free orbit of full measure. We show that such a group $G$ can be quantized in three equivalent ways: (1)…

Operator Algebras · Mathematics 2025-01-24 Pierre Bieliavsky , Victor Gayral , Sergey Neshveyev , Lars Tuset

We study projective unitary (co)representations of compact quantum groups and the associated second cohomology theory. We introduce left/right/bi/strongly projective corepresentations and study them in details. In particular, we prove that…

Quantum Algebra · Mathematics 2026-02-19 Debashish Goswami , Kiran Maity

In this paper, we characterize the families of those bounded linear operators on a separable Hilbert space which are simultaneously unitarily equivalent to integral bi-Carleman operators on $L_2(R)$ having arbitrarily smooth kernels of…

Spectral Theory · Mathematics 2007-05-23 Igor M. Novitskii

In this paper we will demonstrate that any compact quantum group can be used as symmetry groups for quantum channels, which leads us to the concept of covariant channels. We, then, unearth the structure of the convex set of covariant…

Mathematical Physics · Physics 2020-07-09 Hun Hee Lee , Sang-Gyun Youn

Indecomposable symmetric Lorentzian manifolds of non-constant curvature are called Cahen-Wallach spaces. Their isometry classes are described by continuous families of real parameters. We derive necessary and sufficient conditions for the…

Differential Geometry · Mathematics 2015-01-08 Ines Kath , Martin Olbrich

We study the general form of M"obius covariant local commutation relations in conformal chiral quantum field theories and show that they are intrinsically determined up to structure constants, which are subject to an infinite system of…

Mathematical Physics · Physics 2011-08-11 Antonia M. Kukhtina , Karl-Henning Rehren

Compact quantum groups can be studied by investigating their co-representation categories in analogy to the Schur-Weyl/Tannaka-Krein approach. For the special class of (unitary) "easy" quantum groups these categories arise from a…

Combinatorics · Mathematics 2019-07-29 Alexander Mang , Moritz Weber

Let ${\Bbb G}$ be a locally compact quantum group and ${\mathcal T}(L^2({\Bbb G}))$ be the Banach algebra of trace class operators on $L^2({\Bbb G})$ with the convolution induced by the right fundamental unitary of ${\Bbb G}$. We study the…

Operator Algebras · Mathematics 2024-05-20 Mehdi Nemati , Sima Soltani Renani

We consider a class of homogeneous manifolds including all semisimple coadjoint orbits. We describe manifolds of that class admitting deformation q uantizations equivariant under the action of $G$ and the corresponding quantum group. We…

Quantum Algebra · Mathematics 2009-11-07 Joseph Donin , Vadim Ostapenko

Local unitary equivalence is an important ingredient for quantifying and classifying entanglement. Verifying whether or not two quantum states are local unitary equivalent is a crucial problem, where only the case of multipartite pure…

Quantum Physics · Physics 2024-02-27 Qing Zhou , Yi-Zheng Zhen , Xin-Yu Xu , Shuai Zhao , Wen-Li Yang , Shao-Ming Fei , Li Li , Nai-Le Liu , Kai Chen

The category of locally compact quantum groups can be described as either Hopf $*$-homomorphisms between universal quantum groups, or as bicharacters on reduced quantum groups. We show how So{\l}tan's quantum Bohr compactification can be…

Functional Analysis · Mathematics 2021-09-15 Matthew Daws

We introduce compactness classes of Hilbert space operators by grouping together all operators for which the associated singular values decay at a certain speed and establish upper bounds for the norm of the resolvent of operators belonging…

Spectral Theory · Mathematics 2020-05-29 Ayse Guven , Oscar F. Bandtlow

In this paper, we describe families of those bounded linear operators on a separable Hilbert space that are simultaneously unitarily equivalent to integral operators on $L_2(R)$ with bounded and arbitrarily smooth Carleman kernels. The main…

Spectral Theory · Mathematics 2007-05-23 Igor M. Novitskii

In this short note, further to Ng's study, we extend Bekka amenability and weak Bekka amenability to general locally compact quantum groups. We generalize some Ng's results to the general case. In particular, we show that, a locally compact…

Operator Algebras · Mathematics 2018-05-23 Xiao Chen