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The communication complexity of a quantum channel is the minimal amount of classical communication required for classically simulating a process of state preparation, transmission through the channel and subsequent measurement. It…

Quantum Physics · Physics 2012-09-14 Alberto Montina

Quantum theory (QT) has been confirmed by numerous experiments, yet we still cannot fully grasp the meaning of the theory. As a consequence, the quantum world appears to us paradoxical. Here we shed new light on QT by having it follow from…

Quantum Physics · Physics 2019-02-12 Alessio Benavoli , Alessandro Facchini , Marco Zaffalon

We consider a notion of complexity of quantum channels in relativistic continuum quantum field theory (QFT) defined by the distance to the trivial (identity) channel. Our distance measure is based on a specific divergence between quantum…

Quantum Physics · Physics 2025-08-22 Stefan Hollands , Alessio Ranallo

Determining the quantum circuit complexity of a unitary operation is closely related to the problem of finding minimal length paths in a particular curved geometry [Nielsen et al, Science 311, 1133-1135 (2006)]. This paper investigates many…

Quantum Physics · Physics 2007-05-23 Mark R. Dowling , Michael A. Nielsen

It is well known that correlations predicted by quantum mechanics cannot be explained by any classical (local-realistic) theory. The relative strength of quantum and classical correlations is usually studied in the context of Bell…

The geometry of the Quantum State Space, described by Bloch vectors, is a very intricate one. A deeper understanding of this geometry could lead to the solution of some difficult problems in Quantum Foundations and Quantum Information such…

Quantum Physics · Physics 2013-09-30 Jose Ignacio Rosado

Inspired by the work of Feynman, Deutsch, We formally propose the theory of physical computability and accordingly, the physical complexity theory. To achieve this, a framework that can evaluate almost all forms of computation using various…

Computational Physics · Physics 2011-12-06 Huimin Zheng , HaiXing Hu , Nan Wu , Fangmin Song

The idea that the Universe is a program in a giant quantum computer is both fascinating and suffers from various problems. Nonetheless, it can provide a unified picture of physics and this can be very useful for the problem of Quantum…

General Relativity and Quantum Cosmology · Physics 2012-08-03 Fotini Markopoulou

In this expository paper we present a brief introduction to the geometrical modeling of some quantum computing problems. After a brief introduction to establish the terminology, we focus on quantum information geometry and ZX-calculus,…

Quantum Physics · Physics 2024-03-07 E. Ercolessi , R. Fioresi , T. Weber

Any acceptable quantum gravity theory must allow us to recover the classical spacetime in the appropriate limit. Moreover, the spacetime geometrical notions should be intrinsically tied to the behavior of the matter that probes them. We…

General Relativity and Quantum Cosmology · Physics 2018-07-03 Yuri Bonder , Chryssomalis Chryssomalakos , Daniel Sudarsky

Topological phases of matter are often described using auxiliary systems in one extra dimension. I review the one-dimensional cluster state--the simplest quantum state with Symmetry-Protected Topological (SPT) order--as a toy model of…

High Energy Physics - Theory · Physics 2022-01-10 Bartlomiej Czech

We give a definition of uncomplexity of a mixed state without invoking any particular definitions of mixed state complexity, and argue that it gives the amount of computational power Bob has when he only has access to part of a system. We…

High Energy Physics - Theory · Physics 2018-06-19 Ying Zhao

Probabilistic quantum state transformations can be characterized by the degree of state separation they provide. This, in turn, sets limits on the success rate of these transformations. We consider optimum state separation of two known pure…

Quantum Physics · Physics 2016-01-20 Emilio Bagan , Vadim Yerokhin , Andi Shehu , Edgar Feldman , Janos A. Bergou

There are many methods developed to approximate a cloud of vectors embedded in high-dimensional space by simpler objects: starting from principal points and linear manifolds to self-organizing maps, neural gas, elastic maps, various types…

Machine Learning · Statistics 2016-09-01 E. M. Mirkes , A. Zinovyev , A. N. Gorban

We review a geometric approach to classification and examination of quantum correlations in composite systems. Since quantum information tasks are usually achieved by manipulating spin and alike systems or, in general, systems with a finite…

Quantum Physics · Physics 2019-03-27 A. Sawicki , T. Maciążek , M. Oszmaniec , K. Karnas , K. Kowalczyk-Murynka , M. Kuś

This is an introduction to the group field theory approach to quantum gravity, with emphasis on motivations and basic formalism, more than on recent results; we elaborate on the various ingredients, both conceptual and formal, of the…

General Relativity and Quantum Cosmology · Physics 2012-03-27 Daniele Oriti

Quantum geometry on a discrete set means a directed graph with a weight associated to each arrow defining the quantum metric. However, these `lattice spacing' weights do not have to be independent of the direction of the arrow. We use this…

Mathematical Physics · Physics 2020-02-28 Shahn Majid

We study the complexity of computational problems from quantum physics. Typically, they are studied using the complexity class QMA (quantum counterpart of NP) but some natural computational problems appear to be slightly harder than QMA. We…

Quantum Physics · Physics 2014-04-11 Andris Ambainis

These lecture notes are an informal introduction to the theory of computational complexity and its links to quantum computing and statistical mechanics.

Statistical Mechanics · Physics 2009-09-25 Stephan Mertens

Quantum query complexity is a fundamental model for analyzing the computational power of quantum algorithms. It has played a key role in characterizing quantum speedups, from early breakthroughs such as Grover's and Simon's algorithms to…

Quantum Physics · Physics 2025-08-13 Yassine Hamoudi