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The so-called state-carving protocol generates high-fidelity entangled states at an atom-cavity interface without requiring high cavity cooperativity. However, this protocol is limited to 50\% efficiency, which restricts its applicability.…

Quantum states of light with many entangled photons are key resources for photonic quantum computing and quantum communication. In this work, we exploit a highly resource-efficient generation scheme based on a linear optical circuit…

We present general numerical methods to construct witness operators for entanglement detection and estimation of the fidelity. Our methods are applied to detecting entanglement in the vicinity of a six-qubit Dicke state with three…

Design of detection strategies for multipartite entanglement stands as a central importance on our understanding of fundamental quantum mechanics and has had substantial impact on quantum information applications. However, accurate and…

Quantum Physics · Physics 2023-05-24 Xin-Yu Xu , Qing Zhou , Shuai Zhao , Shu-Ming Hu , Li Li , Nai-Le Liu , Kai Chen

In this work, we consider the fundamental task of quantum state certification: given copies of an unknown quantum state $\rho$, test whether it matches some target state $\sigma$ or is $\epsilon$-far from it. For certifying $d$-dimensional…

Quantum Physics · Physics 2026-04-10 Chirag Wadhwa , Sitan Chen

Recently, a technique known as quantum symmetry test has gained increasing attention for detecting bipartite entanglement in pure quantum states. In this work we show that, beyond qualitative detection, a family of well-defined measures of…

Quantum Physics · Physics 2025-11-12 Xiaoyu Liu , Jordi Tura , Albert Rico

A mixed quantum state shared between two parties is said to be distillable if, by means of a protocol involving only local quantum operations and classical communication, the two parties can transform some number of copies of that state…

Quantum Physics · Physics 2009-11-10 John Watrous

Self-testing protocols are methods to determine the presence of shared entangled states in a device independent scenario, where no assumptions on the measurements involved in the protocol are made. A particular type of self-testing…

Quantum Physics · Physics 2021-03-24 Ivan Šupić , Daniel Cavalcanti , Joseph Bowles

Quantum entanglement is an essential resource for quantum technologies, and the controlled swap test provides a versatile tool for its detection and quantification. Here, we propose a SWAP-based entanglement witness that applies to…

Quantum Physics · Physics 2025-12-24 Sebastiano Guaraldo , Sonia Mazzucchi , Alessio Baldazzi , Stefano Azzini , Lorenzo Pavesi

Experimental demonstration of entanglement needs to have a precise control of experimentalist over the system on which the measurements are performed as prescribed by an appropriate entanglement witness. To avoid such trust problem,…

Entanglement, or quantum inseparability, is a crucial resource in quantum information applications, and therefore the experimental generation of separated yet entangled systems is of paramount importance. Experimental demonstrations of…

Quantum Physics · Physics 2009-11-07 M. G. Raymer , A. C. Funk , B. C. Sanders , H. de Guise

Determining whether a quantum state is separable or entangled is a problem of fundamental importance in quantum information science. It has recently been shown that this problem is NP-hard. There is a highly inefficient `basic algorithm'…

Quantum Physics · Physics 2009-11-10 L. M. Ioannou , B. C. Travaglione , D. Cheung , A. K. Ekert

Higher dimensional quantum systems are an important avenue for new explorations in quantum computing as well as quantum communications. One of the ubiquitous resources in quantum technologies is entanglement. However, so far, entanglement…

Quantum Physics · Physics 2019-09-05 Debadrita Ghosh , Thomas Jennewein , Urbasi Sinha

Usually, the three-tangle of a tripartite pure state of qubits can be directly measured with the simultaneous preparation of a not-less-than-four-fold copy of the state. We show that the exact genuine tripartite entanglement for…

Quantum Physics · Physics 2016-04-20 Chang-shui Yu , Bao-qing Guo , Si-ren Yang

Many-body quantum systems can be characterised using the notions of \emph{k}-separability and entanglement depth. A quantum state is \emph{k}-separable if it can be expressed as a mixture of \emph{k} entangled subsystems, and its…

We investigate the detection of entanglement in $n$-partite quantum states. We obtain practical separability criteria to identify genuinely entangled and non-separable mixed quantum states. No numerical optimization or eigenvalue evaluation…

Quantum Physics · Physics 2010-12-15 Ting Gao , Yan Hong

We propose a new scheme to generate the multi-photon entanglement via two steps, that is, first to utilize the superconductor to create the multi-quantum-dot entanglement, and then to use the input photon to transfer it into the…

Quantum Physics · Physics 2015-05-25 Dong Xie , An Min Wang

The experimental detection of multipartite entanglement usually requires a number of appropriately chosen local quantum measurements which are aligned with respect to a previously shared common reference frame. The latter, however, can be a…

Quantum Physics · Physics 2019-04-02 Andreas Ketterer , Nikolai Wyderka , Otfried Gühne

Characterizing entanglement of systems composed of multiple particles is a very complex problem that is attracting increasing attention across different disciplines related to quantum physics. The task becomes even more complex when the…

Quantum Physics · Physics 2026-02-12 Shuheng Liu , Qiongyi He , Marcus Huber , Giuseppe Vitagliano

Quantum entanglement is recognized as a fundamental resource in quantum information processing and is essential for understanding quantum many-body physics. However, experimentally detecting entanglement, particularly in many-particle…

Quantum Physics · Physics 2025-08-13 Hao-Yue Qi , Wei Zheng