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We demonstrate how Quantum Cognition Machine Learning (QCML) encodes data as quantum geometry. In QCML, features of the data are represented by learned Hermitian matrices, and data points are mapped to states in Hilbert space. The quantum…

Quantum coherence is the key resource for quantum technology, with applications in quantum optics, information processing, metrology and cryptography. Yet, there is no universally efficient method for quantifying coherence either in…

Quantum Physics · Physics 2014-10-24 Davide Girolami

The use of geometric methods has proved useful in the hamiltonian description of classical constrained systems. In this note we provide the first steps toward the description of the geometry of quantum constrained systems. We make use of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Alejandro Corichi

We consider the problem of determining the state of a quantum system given one or more readings of the expectation value of an observable. The system is assumed to be a finite dimensional quantum control system for which we can influence…

Quantum Physics · Physics 2009-11-10 Domenico D'Alessandro

In this thesis we provide a uniform treatment of two non-adiabatic geometric phases for dynamical systems of mixed quantum states, namely those of Uhlmann and of Sj\"{o}qvist et al. We develop a holonomy theory for the latter which we also…

Quantum Physics · Physics 2019-10-21 Ole Andersson

The computational complexity of a quantum state quantifies how hard it is to make. `Complexity geometry', first proposed by Nielsen, is an approach to defining computational complexity using the tools of differential geometry. Here we…

High Energy Physics - Theory · Physics 2021-04-01 Adam R. Brown , Leonard Susskind

When studying the geometry of quantum states, it is acknowledged that mixed states can be distinguished by infinitely many metrics. Unfortunately, this freedom causes metric-dependent interpretations of physically significant geometric…

Quantum Physics · Physics 2024-02-07 Paul M. Alsing , Carlo Cafaro , Domenico Felice , Orlando Luongo

We show that the manifold of quantum states is endowed with a rich and nontrivial geometric structure. We derive the Fubini-Study metric of the projective Hilbert space of a multi-qubit quantum system, endowing it with a Riemannian metric…

Quantum Physics · Physics 2024-04-19 Arthur Vesperini , Ghofrane Bel-Hadj-Aissa , Lorenzo Capra , Roberto Franzosi

We express the matrix elements of the density matrix of the qutrit state in terms of probabilities associated with artificial qubit states. We show that the quantum statistics of qubit states and observables is formally equivalent to the…

Quantum Physics · Physics 2018-04-16 Vladimir N. Chernega , Olga V. Man'ko , Vladimir I. Man'ko

The quantum metric, a key component of quantum geometry, plays a central role in a wide range of physical phenomena and has been extensively studied in periodic crystals and moir\'{e} materials. Here, we systematically investigate quantum…

Mesoscale and Nanoscale Physics · Physics 2025-07-08 Jundi Wang , Yuxiao Chen , Huaqing Huang

The aim of the paper is to propose geometric descriptions of multipartite entangled states using algebraic geometry. In the context of this paper, geometric means each stratum of the Hilbert space, corresponding to an entangled state, is an…

Mathematical Physics · Physics 2013-02-12 Frédéric Holweck , Jean-Gabriel Luque , Jean-Yves Thibon

We revisit the representation of generalized quantum observables by establishing a geometric picture in terms of their positive operator-valued measures (POVMs). This leads to a clear geometric interpretation of Born's rule by introducing…

Quantum Physics · Physics 2018-03-02 O. P. Kovalenko , J. Sperling , W. Vogel , A. A. Semenov

A generalised definition of the metric of quantum states is proposed by using the techniques of differential geometry. The metric of quantum state space derived earlier by Anandan, is reproduced and verified here by this generalised…

Quantum Physics · Physics 2007-05-23 Aalok Pandya , Ashok K. Nagawat

The optical properties of solids are governed not only by their energy band dispersions but also by the quantum geometry of Bloch states. While the role of energy bands in determining the perceived optical appearance of materials, such as…

Optics · Physics 2025-07-29 Chang-geun Oh , Sun-Woo Kim

Quantum Hall effects provide intuitive ways of revealing the topology in crystals, i.e., each quantized "step" represents a distinct topological state. Here, we seek a counterpart for "visualizing" quantum geometry, which is a broader…

Quantum Physics · Physics 2025-01-10 B. Q. Song , J. D. H. Smith , T. Jiang , Y. X. Yao , J. Wang

We introduce and explore the notion of texture of an arbitrary quantum state, in a selected basis. In the first part of this letter we develop a resource theory and show that state texture is adequately described by an easily computable…

Quantum Physics · Physics 2025-08-22 Fernando Parisio

Understanding the geometric properties of quantum states and their implications in fundamental physical phenomena is at the core of modern physics. The Quantum Geometric Tensor (QGT) is a central physical object in this regard, encoding…

Geometric and holonomic quantum computation utilizes intrinsic geometric properties of quantum-mechanical state spaces to realize quantum logic gates. Since both geometric phases and quantum holonomies are global quantities depending only…

Quantum Physics · Physics 2023-08-03 Jiang Zhang , Thi Ha Kyaw , Stefan Filipp , Leong-Chuan Kwek , Erik Sjöqvist , Dianmin Tong

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

From statistical distinguishability of probability distributions, one can define distinguishability of quantum states. A corresponding measurement to perform, optimal in a definite sense, for distinguishing between two given states rho_A…

Quantum Physics · Physics 2009-11-11 Asa Ericsson