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The unitary dynamics of quantum systems can be modeled as a trajectory on a Riemannian manifold. This theoretical framework naturally yields a purely geometric interpretation of computational complexity for quantum algorithms, a notion…

Quantum Physics · Physics 2025-07-25 Alberto Acevedo , Antonio Falco

Overparameterized shallow neural networks admit substantial parameter redundancy: distinct parameter vectors may represent the same predictor due to hidden-unit permutations, rescalings, and related symmetries. As a result, geometric…

Machine Learning · Computer Science 2026-03-24 Hang-Cheng Dong , Pengcheng Cheng

The complete quantum metric of a parametrized quantum system has a real part (usually known as the Provost-Vallee metric) and a symplectic imaginary part (known as the Berry curvature). In this paper, we first investigate the relation…

Quantum Physics · Physics 2023-10-02 Balázs Hetényi , Péter Lévay

Consider the Euclidean space $\mathbb{R}^3$ endowed with a canonical semi-symmetric non-metric connection determined by a vector field $\mathsf{C}\in\mathfrak{X}(\mathbb{R}^3)$. We study surfaces when the sectional curvature with respect to…

Differential Geometry · Mathematics 2024-05-22 Muhittin Evren Aydin , Rafael López , Adela Mihai

Krylov complexity has emerged as a new probe of operator growth in a wide range of non-equilibrium quantum dynamics. However, a fundamental issue remains in such studies: the definition of the distance between basis states in Krylov space…

Quantum Physics · Physics 2023-03-14 Chenwei Lv , Ren Zhang , Qi Zhou

We show that there are well separated families of quantum expanders with asymptotically the maximal cardinality allowed by a known upper bound. This has applications to the "growth" of certain operator spaces: It implies asymptotically…

Operator Algebras · Mathematics 2014-12-23 Gilles Pisier

A geometric characterization is given for invertible quantum measurement maps. Denote by ${\mathcal S}(H)$ the convex set of all states (i.e., trace-1 positive operators) on Hilbert space $H$ with dim$H\leq \infty$, and $[\rho_1, \rho_2]$…

Quantum Physics · Physics 2013-02-01 Kan He , Jin-Chuan Hou , Chi-Kwong Li

The mechanism of describing quantum states by standard probability (tomographic one) instead of wave function or density matrix is elucidated. Quantum tomography is formulated in an abstract Hilbert space framework, by means of the identity…

Quantum Physics · Physics 2008-11-26 V. I. Man'ko , G. Marmo , A. Simoni , A. Stern , E. C. G. Sudarshan , F. Ventriglia

The long standing problem of the ordering ambiguity in the definition of the Hamilton operator for a point particle in curved space is naturally resolved by using the powerful geometric calculus based on Clifford Algebra. The momentum…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Matej Pavsic

In this note, we define a bounded variant on the Hilbert projective metric on an infinite dimensional space $E$ and study the contraction properties of the projective maps associated with positive linear operators on $E$. More precisely, we…

Functional Analysis · Mathematics 2025-02-07 Maxime Ligonnière

The basic notions of quantum mechanics are formulated in terms of separable infinite dimensional Hilbert space $\mathcal{H}$. In terms of the Hilbert lattice $\mathcal{L}$ of closed linear subspaces of $\mathcal{H}$ the notions of state and…

Logic in Computer Science · Computer Science 2023-06-22 Eike Neumann , Martin Pape , Thomas Streicher

Given a complex manifold $X$ and a smooth positive function $\eta$ thereon, we perturb the standard differential operator $d=\partial + \bar\partial$ acting on differential forms to a first-order differential operator $D_\eta$ whose…

Differential Geometry · Mathematics 2024-11-21 Dan Popovici

Building on the recently introduced notion of quantum Ricci curvature and motivated by considerations in nonperturbative quantum gravity, we advocate a new, global observable for curved metric spaces, the curvature profile. It is obtained…

General Relativity and Quantum Cosmology · Physics 2021-02-03 J. Brunekreef , R. Loll

An important conjecture within the AdS/CFT correspondence relates holographic spacetime to the quantum computational complexity of the dual quantum field theory. However, the quantitative understanding of this relation is still an open…

High Energy Physics - Theory · Physics 2022-12-02 Johanna Erdmenger , Marius Gerbershagen , Michal P. Heller , Anna-Lena Weigel

Quantum computational complexity estimates the difficulty of constructing quantum states from elementary operations, a problem of prime importance for quantum computation. Surprisingly, this quantity can also serve to study a completely…

High Energy Physics - Theory · Physics 2022-03-02 Shira Chapman , Giuseppe Policastro

We determine the scaling properties of geometric operators such as lengths, areas, and volumes in models of higher derivative quantum gravity by renormalizing appropriate composite operators. We use these results to deduce the fractal…

General Relativity and Quantum Cosmology · Physics 2020-04-22 Maximilian Becker , Carlo Pagani , Omar Zanusso

In physics, two systems that radically differ at short scales can exhibit strikingly similar macroscopic behaviour: they are part of the same long-distance universality class. Here we apply this viewpoint to geometry and initiate a program…

High Energy Physics - Theory · Physics 2023-11-22 Adam R. Brown , Michael H. Freedman , Henry W. Lin , Leonard Susskind

We establish several inequalities for manifolds with positive scalar curvature and, more generally, for the scalar curvature bounded from below, in the spirit of the classical bound on the distances between conjugates points in surfaces…

Differential Geometry · Mathematics 2018-10-30 Misha Gromov

Symmetries impose structure on the Hilbert space of a quantum mechanical model. The mathematical units of this structure are the irreducible representations of symmetry groups and I consider how they function as conceptual units of…

Quantum Physics · Physics 2018-01-29 N. L. Harshman

The main purpose of this paper is to determine the admissible forms of the sectional curvature operator on a three-dimensional locally homogeneous Lorentzian manifolds.

Differential Geometry · Mathematics 2018-09-10 O. P. Khromova , S. V. Klepikova , E. D. Rodionov