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We show that two related measures of k-coherence, called the standard and generalized robustness of k-coherence, are equal to each other when restricted to pure states. As a direct application of the result, we establish an equivalence…

Quantum Physics · Physics 2018-08-29 Nathaniel Johnston , Chi-Kwong Li , Sarah Plosker , Yiu-Tung Poon , Bartosz Regula

In the standard geometric approach, the entanglement of a pure state is $\sin^2\theta$, where $\theta$ is the angle between the entangled state and the closest separable state of products of normalised qubit states. We consider here a…

Quantum Physics · Physics 2015-05-18 M. E. Carrington , R. Kobes , G. Kunstatter , D. Ostapchuk , G. Passante

Several inequivalent definitions of the geometric measure of entanglement (GM) have been introduced and studied in the past. Here we review several known and new definitions, with the qualifying criterion being that for pure states the…

Quantum Physics · Physics 2014-04-18 Lin Chen , Martin Aulbach , Michal Hajdusek

Coherence and entanglement are fundamental properties of quantum systems, promising to power the near future quantum computers, sensors and simulators. Yet, their experimental detection is challenging, usually requiring full reconstruction…

Quantum Physics · Physics 2017-08-01 Graeme Smith , John A. Smolin , Xiao Yuan , Qi Zhao , Davide Girolami , Xiongfeng Ma

We point out that a geometric measure of quantum entanglement is related to the matrix permanent when restricted to permutation invariant states. This connection allows us to interpret the permanent as an angle between vectors. By employing…

Quantum Physics · Physics 2011-12-30 Tzu-Chieh Wei , Simone Severini

Quantum coherence is an essential ingredient in quantum information processing and plays a central role in emergent fields such as nanoscale thermodynamics and quantum biology. However, our understanding and quantitative characterization of…

All the $n(2n+3)$ mean and covariance parameters of an $n$-mode Gaussian states are expressed in terms of the expectation values of the same number of conjugates of the total number observable. This permits a complete tomography of the…

Quantum Physics · Physics 2016-01-14 K. R. Parthasarathy , Ritabrata Sengupta

Computing entanglement of an arbitrary bipartite or multipartite mixed state is in general not an easy task as it usually involves complex optimization. Here we show that exploiting symmetries of certain mixed states, we can compute a…

Quantum Physics · Physics 2016-08-31 Tamoghna Das , Sudipto Singha Roy , Shrobona Bagchi , Avijit Misra , Aditi Sen De , Ujjwal Sen

Purity and coherence of a quantum state are recognized as useful resources for various information processing tasks. In this article, we propose a fidelity based valid measure of purity and coherence monotone and establish a relationship…

Quantum Physics · Physics 2021-04-09 Indrajith V S , R. Muthuganesan , R. Sankaranarayanan

Trends of genuine entanglement in Haar uniformly generated multimode pure Gaussian states with fixed average energy per mode are explored. A distance-based metric known as the generalized geometric measure (GGM) is used to quantify genuine…

Quantum Physics · Physics 2024-04-29 Saptarshi Roy

Quantum information is a common topic of research in many areas of quantum physics, such as quantum communication and quantum computation, as well as quantum thermodynamics. It can be encoded in discrete or continuous variable systems, with…

Quantum Physics · Physics 2021-03-25 Jonas F. G. Santos , Carlos H. S. Vieira , Pedro R. Dieguez

Quantum steering---a strong correlation to be verified even when one party or its measuring device is fully untrusted---not only provides a profound insight into quantum physics but also offers a crucial basis for practical applications.…

Quantum Physics · Physics 2016-07-18 Se-Wan Ji , Jaehak Lee , Jiyong Park , Hyunchul Nha

Quantum information characteristics, such as quantum mutual information, loss, noise and coherent information are explicitly calculated for Bosonic attenuation/amplification channel with input Gaussian state. The coherent information is…

Quantum Physics · Physics 2007-05-23 Alexander S. Holevo

A necessary and sufficient condition for characterization and quantification of entanglement of any bipartite Gaussian state belonging to a special symmetry class is given in terms of classicality measures of one-party states. For Gaussian…

Quantum Physics · Physics 2009-11-10 M. C. de Oliveira

The well-known two-slit interference is understood as a special relation between observable (localization at the slits) and state (being on both slits). Relation between an observable and a quantum state is investigated in the general case.…

Quantum Physics · Physics 2009-11-11 Fedor Herbut

In this thesis there are two topics: On the entangling capacity, in terms of negativity, of quantum operations, and on the supremum of negativity for symmetric Gaussian states. Positive partial transposition (PPT) states are an important…

Quantum Physics · Physics 2020-08-12 Jhih-Yuan Kao

The coherence resource theory needs to study the operational value and efficiency which can be broadly formulated as the question: when can one coherent state be converted into another under incoherent operations. We answer this question…

Quantum Physics · Physics 2022-02-15 Shuanping Du , Zhaofang Bai

Recently, an explicit relation between a measure of entanglement and a geometric entity has been reported in Quantum Inf. Process. (2016) 15:1629-1638. It has been shown that if a qubit gets entangled with another ancillary qubit then…

Quantum Physics · Physics 2019-04-10 Pratapaditya Bej , Prasenjit Deb

We give an introduction to Gaussian states and operations. A discussion of the entanglement properties of bipartite Gaussian states in terms of its covariance matrix follows. It is explained how entanglement can be witnessed using feasible…

Quantum Physics · Physics 2007-05-23 Janet Anders

We do not observe quantum effects on cosmological scales. Thus, if loop quantum cosmology (LQC) is to provide an accurate depiction of the real world, it must allow for quantum states of spacetime geometry which are semi-classical in two…

General Relativity and Quantum Cosmology · Physics 2021-04-28 Patrick Fraser