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We study a system of two tunnel-coupled quantum dots, with the first dot containing interacting electrons (described by the Universal Hamiltonian) not subject to spin-orbit coupling, whereas the second contains non-interacting electrons…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 Oleksandr Zelyak , Ganpathy Murthy

We find a consistent formulation of the constraints of Quantum Gravity with a cosmological constant in terms of the Ashtekar new variables in the connection representation, including the existence of a state that is a solution to all the…

High Energy Physics - Theory · Physics 2008-11-26 Bernd Bruegmann , Rodolfo Gambini , Jorge Pullin

The entanglement of a pure state of a pair of quantum systems is defined as the entropy of either member of the pair. The entanglement of formation of a mixed state is defined as the minimum average entanglement of an ensemble of pure…

Quantum Physics · Physics 2009-01-23 William K. Wootters

Quantum information is about the entanglement of states. To this starting point we add parameters whereby a single state becomes a non-vanishing section of a bundle. We consider through examples the possible entanglement patterns of…

Quantum Physics · Physics 2023-11-23 M. H. Freedman , M. B. Hastings

Quantum operations describe any state change allowed in quantum mechanics, including the evolution of an open system or the state change due to a measurement. In this letter we present a general method based on quantum tomography for…

Quantum Physics · Physics 2009-11-06 G. M. D'Ariano , P. Lo Presti

This survey gives a comprehensive account of quantum correlations understood as a phenomenon stemming from the rules of quantization. Centered on quantum probability it describes the physical concepts related to correlations (both classical…

Quantum Physics · Physics 2015-05-22 W. A. Majewski

We discuss and implement experimentally a method for characterizing quantum gates operating on superpositions of coherent states. The peculiarity of this encoding of qubits is to work with a non-orthogonal basis, and therefore some…

Entanglement entropy, which is a measure of quantum correlations between separate parts of a many-body system, has emerged recently as a fundamental quantity in broad areas of theoretical physics, from cosmology and field theory to…

Quantum Physics · Physics 2009-03-09 Israel Klich , Leonid Levitov

An entangled quantum state of two or more particles or objects exhibits some of the most peculiar features of quantum mechanics. Entangled systems cannot be described independently of each other even though they may have an arbitrarily…

Mesoscale and Nanoscale Physics · Physics 2018-04-27 C. F. Ockeloen-Korppi , E. Damskagg , J. -M. Pirkkalainen , A. A. Clerk , F. Massel , M. J. Woolley , M. A. Sillanpaa

One of the key manifestations of quantum mechanics is the phenomenon of quantum entanglement. While the entanglement of bipartite systems is already well understood, our knowledge of entanglement in multipartite systems is still limited.…

Quantum Physics · Physics 2022-04-29 Adam Burchardt

Quantum metrology based on quantum entanglement and quantum coherence improves the accuracy of measurement. In this paper, we briefly review the schemes of quantum metrology in various complex systems, including non-Markovian noise,…

Quantum Physics · Physics 2024-01-18 Qing Ai , Yang-Yang Wang , Jing Qiu

The quantum walk is a dynamical protocol which describes the motion of spinful particles on a lattice. Also, it has been demonstrated to be a powerful platform to explore topological quantum matter. Recently, the quantum walk in coherent…

Quantum Physics · Physics 2018-09-19 Zi-Yong Ge , Heng Fan

We analyze the interplay of chaos, entanglement and decoherence in a system of qubits whose collective behaviour is that of a quantum kicked top. The dynamical entanglement between a single qubit and the rest can be calculated from the mean…

Quantum Physics · Physics 2009-11-13 S. Ghose , R. Stock , P. S. Jessen , R. Lal , A. Silberfarb

We study the quantum correlations in a 2D system that possesses a topological quantum phase transition. The quantumness of two-body correlations is measured by quantum discord. We calculate both the correlation of two local spins and that…

Quantum Physics · Physics 2015-05-14 Yi-Xin Chen , Sheng-Wen Li

The geometric measure of entanglement of a pure quantum state is defined to be its distance to the space of product (seperable) states. Given an $n$-partite system composed of subsystems of dimensions $d_1,\ldots, d_n$, an upper bound for…

Quantum Physics · Physics 2018-05-09 Liqun Qi , Guofeng Zhang , Guyan Ni

It is demonstrated that in gate-based quantum computing architectures quantum walk is a natural mathematical description of quantum gates. It originates from field-matter interaction driving the system, but is not attached to specific qubit…

Quantum Physics · Physics 2020-05-08 Dmitry Solenov

We define predictive states and predictive complexity for quantum systems composed of distinct subsystems. This complexity is a generalization of entanglement entropy. It is inspired by the statistical or forecasting complexity of…

Quantum Physics · Physics 2024-10-22 Curtis T. Asplund , Elisa Panciu

The collapse of a quantum state can be understood as a mathematical way to construct a joint probability density even for operators that do not commute. We can formalize that construction as a non-commutative, non-associative collapse…

Quantum Physics · Physics 2022-06-13 Peter Morgan

With any state of a multipartite quantum system its separability polytope is associated. This is an algebro-topological object (non-trivial only for mixed states) which captures the localisation of entanglement of the state. Particular…

Quantum Physics · Physics 2015-06-26 Roman R. Zapatrin

Loop Quantum Gravity defines the quantum states of space geometry as spin networks and describes their evolution in time. We reformulate spin networks in terms of harmonic oscillators and show how the holographic degrees of freedom of the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Florian Girelli , Etera R. Livine