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The quantum geometric tensor (QGT) is a fundamental concept for characterizing the local geometry of quantum states. After casting the geometry of pure quantum states and extracting the QGT, we generalize the geometry to mixed quantum…

Quantum Physics · Physics 2024-07-19 Xu-Yang Hou , Zheng Zhou , Xin Wang , Hao Guo , Chih-Chun Chien

The elements of a deterministic quantum theory are developed, which reformulates and extends standard quantum theory. The proposed theory is `realistic' in the sense that in it, a general M-level quantum state is represented by a single…

Quantum Physics · Physics 2007-05-23 T. N. Palmer

Characterizing complex quantum systems is a vital task in quantum information science. Quantum tomography, the standard tool used for this purpose, uses a well-designed measurement record to reconstruct quantum states and processes. It is,…

Quantum Physics · Physics 2015-12-10 Amir Kalev , Robert L. Kosut , Ivan H. Deutsch

We show that partial transposition for pure and mixed two-particle states in a discrete $N$-dimensional Hilbert space is equivalent to a change in sign of a "momentum-like" variable of one of the particles in the Wigner function for the…

Quantum Physics · Physics 2017-05-29 Yehuda B. Band , Pier A. Mello

We study the holographic properties of a class of quantum geometry states characterized by a superposition of discrete geometric data, in the form of generalised tensor networks. This class specifically includes spin networks, the kinematic…

Quantum Physics · Physics 2024-02-28 Eugenia Colafranceschi , Simon Langenscheidt , Daniele Oriti

Quantisation on spaces with properties of curvature, multiple connectedness and non orientablility is obtained. The geodesic length spectrum for the Laplacian operator is extended to solve the Schroedinger operator. Homotopy fundamental…

Quantum Physics · Physics 2007-05-23 Ajay Patwardhan

Reconstructing the full quantum state of a many-body system requires the estimation of a number of parameters that grows exponentially with system size. Nevertheless, there are situations in which one is only interested in a subset of these…

Quantum Physics · Physics 2023-02-08 Bruna G. M. Araújo , Márcio M. Taddei , Daniel Cavalcanti , Antonio Acín

A generalization of the geometric measure of quantum discord is introduced in this article, based on Hellinger distance. Our definition has virtues of computability and independence of local measurement. In addition it also does not suffer…

Quantum Physics · Physics 2016-02-02 Hai-Tao Cui , Jun-Long Tian , Gui Yang

We report on an intrinsic relationship between the maximum-likelihood quantum-state estimation and the representation of the signal. A quantum analogy of the transfer function determines the space where the reconstruction should be done…

Quantum Physics · Physics 2009-11-13 Z. Hradil , D. Mogilevtsev , J. Rehacek

Quantum tomography can reconstruct fine phase-space structures that are not necessarily resolved by measurement itself. We show that the effective resolution of tomography is determined by a sampling operator linked to the Gram matrix of…

Quantum Physics · Physics 2026-05-29 Zdenek Hradil , Jaroslav Rehacek

Is the dynamical evolution of physical systems objectively a manifestation of information processing by the universe? We find that an affirmative answer has important consequences for the measurement problem. In particular, we calculate the…

Quantum Physics · Physics 2007-05-23 R. Srikanth

Why do we need quantization to describe vision? What are the quadrature operators of the electromagnetic field? Is it possible to measure them? What are the characteristic functions useful for? In this brief tutorial we provide the…

Quantum Physics · Physics 2021-10-08 Stefano Olivares

We present a novel method to perform quantum state tomography for many-particle systems which are particularly suitable for estimating states in lattice systems such as of ultra-cold atoms in optical lattices. We show that the need for…

Quantum Physics · Physics 2015-06-04 M. Ohliger , V. Nesme , J. Eisert

The core of quantum tomography is the possibility of writing a generally unbounded complex operator in form of an expansion over operators that are generally nonlinear functions of a generally continuous set of spectral densities--the…

Quantum Physics · Physics 2015-05-13 G. M. D'Ariano , M. F. Sacchi

The existing relation between the tomographic description of quantum states and the convolution algebra of certain discrete groupoids represented on Hilbert spaces will be discussed. The realizations of groupoid algebras based on qudit,…

Mathematical Physics · Physics 2015-06-17 A. Ibort , V. I. Manko , G. Marmo , A. Simoni , C. Stornaiolo

It is proposed the scheme of quantum mechanics, in which a Hilbert space and the linear operators are not primary elements of the theory. Instead of it certain variant of the algebraic approach is considered. The elements of noncommutative…

Quantum Physics · Physics 2007-05-23 D. A. Slavnov

In quantum physics, multiparticle systems are described by quantum states acting on tensor products of Hilbert spaces. This product structure leads to the distinction between product states and entangled states; moreover, one can quantify…

Quantum Physics · Physics 2026-03-06 Lisa T. Weinbrenner , Albert Rico , Kenneth Goodenough , Xiao-Dong Yu , Otfried Gühne

A quantum system can be entirely described by the K\"ahler structure of the projective space P(H) associated to the Hilbert space H of possible states; this is the so-called geometrical formulation of quantum mechanics. In this paper, we…

Differential Geometry · Mathematics 2012-02-07 Mathieu Molitor

Quantum information geometry studies families of quantum states by means of differential geometry. A new approach is followed with the intention to facilitate the introduction of a more general theory in subsequent work. To this purpose,…

Mathematical Physics · Physics 2018-08-01 Jan Naudts

We propose the assumption of quantum mechanics on a discrete space and time, which implies the modification of mathematical expressions for some postulates of quantum mechanics. In particular we have a Hilbert space where the vectors are…

Quantum Physics · Physics 2007-05-23 M. Lorente