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Entanglement breaking (EB) channels, as completely positive and trace-preserving linear operators, sever the entanglement between the input system and other systems. In the realm of infinite-dimensional systems, a related concept known as…

Functional Analysis · Mathematics 2024-10-28 Bui Ngoc Muoi , Nung-Sing Sze

We report an experiment in which one determines, with least tomographic effort, whether an unknown two-photon polarization state is entangled or separable. The method measures whole families of optimal entanglement witnesses. We introduce…

Quantum Physics · Physics 2014-10-29 Jibo Dai , Yink Loong Len , Yong Siah Teo , Berthold-Georg Englert , Leonid A. Krivitsky

We provide two 1-parameter families of indecomposable entanglement witnesses in C4 {\otimes} C4. Following recent paper by Ha and Kye [Phys. Rev. A 84, 024302 (2011)] we show that these EWs are optimal and hence provide the strongest tool…

Quantum Physics · Physics 2012-04-25 Dariusz Chruściński , Filip A. Wudarski

The set of Entanglement Saving (ES) quantum channels is introduced and characterized. These are completely positive, trace preserving transformations which when acting locally on a bipartite quantum system initially prepared into a…

Quantum Physics · Physics 2016-05-24 Ludovico Lami , Vittorio Giovannetti

We provide a constructive algorithm to find the best separable approximation to an arbitrary density matrix of a composite quantum system of finite dimensions. The method leads to a condition of separability and to a measure of…

Quantum Physics · Physics 2009-10-30 Maciej Lewenstein , Anna Sanpera

Entanglement witness is an effective method to detect entanglement in unknown states without doing full tomography. One of the most widespread schemes of witnessing entanglement is measuring its fidelity with respect to a pure entangled…

Quantum Physics · Physics 2021-03-19 Yongtao Zhan , Hoi-Kwong Lo

Weakly supervised object localization(WSOL) remains an open problem given the deficiency of finding object extent information using a classification network. Although prior works struggled to localize objects through various spatial…

Computer Vision and Pattern Recognition · Computer Science 2021-03-31 Xingjia Pan , Yingguo Gao , Zhiwen Lin , Fan Tang , Weiming Dong , Haolei Yuan , Feiyue Huang , Changsheng Xu

Entanglement witnesses provide a standard tool for the analysis of entanglement in experiments. We investigate possible nonlinear entanglement witnesses from several perspectives. First, we demonstrate that they can be used to show that the…

Quantum Physics · Physics 2007-06-13 Otfried Gühne , Norbert Lütkenhaus

Entanglement, the essential resource in quantum information processing, should be witnessed in many tasks such as quantum computing and quantum communication. The conventional entanglement witness method, relying on an idealized…

Quantum Physics · Physics 2014-04-17 Ping Xu , Xiao Yuan , Luo-Kan Chen , He Lu , Xing-Can Yao , Xiongfeng Ma , Yu-Ao Chen , Jian-Wei Pan

Genuine multipartite entanglement is arguably the most valuable form of entanglement in the multipartite case, with applications, for instance, in quantum metrology. In order to detect that form of entanglement in multipartite quantum…

Quantum Physics · Physics 2026-04-07 Jakub Szczepaniak , Owidiusz Makuta , Remigiusz Augusiak

Let $H^{[ N]}=H^{[ d_{1}]}\otimes ... \otimes H^{[ d_{n}]}$ be a tensor product of Hilbert spaces and let $\tau_{0}$ be the closest separable state in the Hilbert-Schmidt norm to an entangled state $\rho_{0}$. Let $\tilde{\tau}_{0}$ denote…

Quantum Physics · Physics 2009-11-07 Arthur O. Pittenger , Morton H. Rubin

We give a universal recipe for constructing nonlinear entanglement witnesses able to detect non-classical correlations in arbitrary systems of distinguishable and/or identical particles for an arbitrary number of constituents. The…

Quantum Physics · Physics 2013-05-29 Marcin Kotowski , Michal Kotowski , Marek Kus

We frame entanglement detection as a problem of random variable inference to introduce a quantitative method to measure and understand whether entanglement witnesses lead to an efficient procedure for that task. Hence we quantify how many…

Quantum Physics · Physics 2023-08-16 Paulo J. Cavalcanti , Giovanni Scala , Antonio Mandarino , Cosmo Lupo

Entanglement detection is one of the most fundamental tasks in quantum information science, playing vital roles in theoretical studies and quantum system benchmarking. Researchers have proposed many powerful entanglement criteria with high…

Quantum Physics · Physics 2024-03-05 Zhenhuan Liu , Fuchuan Wei

We introduce the \emph{CP-distance} to quantify the deviation of Hermitian linear maps from complete positivity, defined as the minimal depolarizing noise required to render a map completely positive. We derive a closed spectral formula for…

Quantum Physics · Physics 2026-01-06 Mohsen Kian

We study entanglement witness and present a construction of entanglement witnesses in terms of the symmetric informationally complete measurements (SIC-POVM). The capability of our witness is shown by some examples and it can be found this…

Quantum Physics · Physics 2020-11-04 Tao Li , Le-Min Lai , Deng-Feng Liang , Shao-Ming Fei , Zhi-Xi Wang

We show that every entanglement with positive partial transpose may be constructed from an indecomposable positive linear map between matrix algebras.

Quantum Physics · Physics 2009-11-10 Kil-Chan Ha , Seung-Hyeok Kye

The problem of entanglement detection is a long standing problem in quantum information theory. One of the primary procedures of detecting entanglement is to find the suitable positive but non-completely positive maps. Here we try to give a…

How can a multipartite single-photon path-entangled state be certified efficiently by means of local measurements? We address this question by constructing an entanglement witness based on local photon detections preceded by displacement…

The pixel-wise dense prediction tasks based on weakly supervisions currently use Class Attention Maps (CAM) to generate pseudo masks as ground-truth. However, the existing methods typically depend on the painstaking training modules, which…

Computer Vision and Pattern Recognition · Computer Science 2021-11-08 Yanpeng Sun , Zechao Li