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Quantum network is a set of nodes connected with channels, through which the nodes communicate photons and classical information. Classical structural complexity of a quantum network may be defined through its physical structure, i.e.…

Quantum Physics · Physics 2016-06-20 Michael Siomau

Science is rich in abstract concepts that capture complex processes in astonishingly simple ways. A prominent example is the reduction of molecules to simple graphs. This work introduces a design principle for parametrized quantum circuits…

Quantum Physics · Physics 2023-08-09 Jakob S. Kottmann

The properties which give quantum mechanics its unique character - unitarity, complementarity, non-commutativity, uncertainty, nonlocality - derive from the algebraic structure of Hermitian operators acting on the wavefunction in complex…

Quantum Physics · Physics 2022-09-14 Tim Palmer

Geometric complexity theory (GCT) is an approach to the P vs. NP and related problems. This article gives its complexity theoretic overview without assuming any background in algebraic geometry or representation theory.

Computational Complexity · Computer Science 2009-08-19 Ketan D. Mulmuley

An alternative model to describe the electronic and thermal properties of quantum dot based on triangle geometry is proposed. The model predicts characteristics and limitations of the system by controlling the magnetic field and…

Mesoscale and Nanoscale Physics · Physics 2023-02-10 Francisco A. G. de Lira , Edilberto O. Silva

After recalling briefly some basic properties of the quantum group $GL_q(2)$, we study the quantum sphere $S_q^2$, quantum projective space $CP_q(N)$ and quantum Grassmannians as examples of complex (K\"{a}hler) quantum manifolds. The…

High Energy Physics - Theory · Physics 2007-05-23 Chong-Sun Chu , Pei-Ming Ho , Bruno Zumino

When it comes to NP, its natural definition, its wide applicability across scientific disciplines, and its timeless relevance, the writing is on the wall: There can be only one. Quantum NP, on the other hand, is clearly the apple that fell…

Quantum Physics · Physics 2024-01-09 Sevag Gharibian

This paper considers the realizability of quantum gates from the perspective of information complexity. Since the gate is a physical device that must be controlled classically, it is subject to random error. We define the complexity of gate…

Quantum Physics · Physics 2009-11-11 Subhash Kak

Taking the view that computation is after all physical, we argue that physics, particularly quantum physics, could help extend the notion of computability. Here, we list the important and unique features of quantum mechanics and then…

Quantum Physics · Physics 2007-05-23 Tien D Kieu

The quantum deformation $CP_q(N)$ of complex projective space is discussed. Many of the features present in the case of the quantum sphere can be extended. The differential and integral calculus is studied and $CP_q(N)$ appears as a quantum…

q-alg · Mathematics 2009-10-28 Chong-Sun Chu , Pei-Ming Ho , Bruno Zumino

The intuition that a long history is required for the emergence of complexity in natural systems is formalized using the notion of depth. The depth of a system is defined in terms of the number of parallel computational steps needed to…

Statistical Mechanics · Physics 2011-11-09 J. Machta

A quantum system's state is identified with a density matrix. Though their probabilistic interpretation is rooted in ensemble theory, density matrices embody a known shortcoming. They do not completely express an ensemble's physical…

Quantum Physics · Physics 2021-06-30 Fabio Anza , James P. Crutchfield

We present a geometrical description of the space of density states of a quantum system of finite dimension. After presenting a brief summary of the geometrical formulation of Quantum Mechanics, we proceed to describe the space of density…

Quantum Physics · Physics 2007-07-26 J. Clemente-Gallardo , G. Marmo

In the first part of this review we introduce the basics theory behind geometric phases and emphasize their importance in quantum theory. The subject is presented in a general way so as to illustrate its wide applicability, but we also…

Quantum Physics · Physics 2007-05-23 Vlatko Vedral

The physically allowed quantum evolutions on a single qubit can be described in terms of their geometry. From a simple parameterisation of unital single-qubit channels, the canonical form of all such channels can be given. The related…

Quantum Physics · Physics 2007-05-23 D. K. L. Oi

Quantum entanglement between several particles is essential for applications like quantum metrology or quantum cryptography, but it is also central for foundational phenomena like quantum non-locality. This leads to the problem of…

Quantum Physics · Physics 2025-10-10 Lisa T. Weinbrenner , Otfried Gühne

We survey various recent results that rigorously study the complexity of learning quantum states. These include progress on quantum tomography, learning physical quantum states, alternate learning models to tomography and learning classical…

Quantum Physics · Physics 2023-06-01 Anurag Anshu , Srinivasan Arunachalam

Quantum Computing is a new and exciting field at the intersection of mathematics, computer science and physics. It concerns a utilization of quantum mechanics to improve the efficiency of computation. Here we present a gentle introduction…

Quantum Physics · Physics 2007-08-03 Noson S. Yanofsky

In this article the geometry of quantum gravity is quantized in the sense of being noncommutative (first quantization) but it is also quantized in the sense of being emergent (second quantization). A new mechanism for quantum geometry is…

High Energy Physics - Theory · Physics 2022-06-29 Badis Ydri , Ramda Khaled , Cherine Soudani

Every quantum state can be represented as a probability distribution over the outcomes of an informationally complete measurement. But not all probability distributions correspond to quantum states. Quantum state space may thus be thought…

Quantum Physics · Physics 2011-02-14 D. M. Appleby , Asa Ericsson , Christopher A. Fuchs