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Detection of entanglement through partial knowledge of the quantum state is a challenge to implement efficiently. Here we propose a separability criterion for detecting bipartite entanglement in arbitrary dimensional quantum states using…

Quantum Physics · Physics 2024-05-28 Shruti Aggarwal , Satyabrata Adhikari , A. S. Majumdar

We consider entanglement detection for quantum key distribution systems that use two signal states and continuous variable measurements. This problem can be formulated as a separability problem in a qubit-mode system. To verify…

Quantum Physics · Physics 2007-05-23 Johannes Rigas , Otfried Gühne , Norbert Lütkenhaus

Efficiently certifying non-Gaussian entanglement in continuous-variable quantum systems is a central challenge for advancing quantum information processing, photonic quantum computing, and metrology. Here, we put forward continuous-variable…

Quantum Physics · Physics 2025-04-23 Serge Deside , Tobias Haas , Nicolas J. Cerf

Random local measurements have recently been proposed to construct entanglement witnesses and thereby detect the presence of bipartite entanglement. We experimentally demonstrate the efficacy of one such scheme on a two-qubit NMR quantum…

Quantum Physics · Physics 2016-12-13 Amandeep Singh , Arvind , Kavita Dorai

Multipartite entanglement is an essential resource for quantum information tasks, but characterizing entanglement structures in continuous variable systems remains challenging, especially in multimode non-Gaussian scenarios. In this work,…

Quantum Physics · Physics 2025-11-03 Mingsheng Tian , Xiaoting Gao , Boxuan Jing , Feng-Xiao Sun , Matteo Fadel , Manuel Gessner , Qiongyi He

In this paper, we propose a method to probe entanglement in a theoretically inaccessible quantum system with either a discrete or continuous basis. Our approach leverages insights into the entanglement distribution within a four-partite…

Quantum Physics · Physics 2025-07-10 Pablo C. López Vázquez , Luis M. Piñuelas , Gustavo Montes

We show with explicit formulas that one can completely identify an unknown quantum process with only one weakly entangled state; and identify a quantum optical Gaussian process with either one two-mode squeezed state or a few different…

Quantum Physics · Physics 2010-10-05 Xiang-Bin Wang , J. -Z. Hu , Z. -W. Yu , Franco Nori

Entangled two-mode Gaussian states are a key resource for quantum information technologies such as teleportation, quantum cryptography and quantum computation, so quantification of Gaussian entanglement is an important problem. Entanglement…

Quantum Physics · Physics 2018-01-03 Spyros Tserkis , Timothy C. Ralph

Quantum universal invariants of a Gaussian state's covariance matrix, which can be derived from intensity correlation moments, have been adopted to characterize the entanglement properties of Gaussian states via the positive partial…

Quantum Physics · Physics 2026-05-01 Ze-Shan He , Yukuan Zhao , Hao-Shu Tian , Kai Sun , Xiao-Ye Xu , Chuan-Feng Li , Guang-Can Guo

The concept of entangled quantum states is considered in the context of systems of identical particles, based on the requirement that in order to represent physical states both for the overall system and the sub-systems which may be…

Quantum Physics · Physics 2014-01-03 Bryan Dalton , Libby Heaney , John Goold , Thomas Busch , Barry Garraway

We present a method to test quantum behavior of quantum information processing devices, such as quantum memories, teleportation devices, channels and quantum key distribution protocols. The test of quantum behavior can be phrased as the…

Quantum Physics · Physics 2008-03-07 Hauke Häseler , Tobias Moroder , Norbert Lütkenhaus

The recognition of entanglement states is a notoriously difficult problem when no prior information is available. Here, we propose an efficient quantum adversarial bipartite entanglement detection scheme to address this issue. Our proposal…

We present a new approach to the analysis of entanglement in smooth bipartite continuous-variable states. One or both parties perform projective filterings via preliminary measurements to determine whether the system is located in some…

Quantum Physics · Physics 2009-11-13 H. -C. Lin , A. J. Fisher

Detecting genuine multipartite entanglement (GME) is a state-characterization task that benchmarks coherence and experimental control in quantum systems. Existing GME tests often require joint measurements on many qubits, posing challenges…

Quantum Physics · Physics 2026-02-18 Nicky Kai Hong Li , Xi Dai , Manuel H. Muñoz-Arias , Kevin Reuer , Marcus Huber , Nicolai Friis

We review the theory of continuous-variable entanglement with special emphasis on foundational aspects, conceptual structures, and mathematical methods. Much attention is devoted to the discussion of separability criteria and entanglement…

Quantum Physics · Physics 2009-07-02 Gerardo Adesso , Fabrizio Illuminati

Entanglement, while being critical in many quantum applications, is difficult to characterize experimentally. While entanglement witnesses based on the fidelity to the target entangled state are efficient detectors of entanglement, they in…

Quantum Physics · Physics 2020-01-29 Won Kyu Calvin Sun , Alexandre Cooper , Paola Cappellaro

Detecting entanglement in many-body quantum systems is crucial but challenging, typically requiring multiple measurements. Here, we establish the class of states where measuring connected correlations in just $\textit{one}$ basis is…

Quantum Physics · Physics 2024-04-05 Roopayan Ghosh , Sougato Bose

Quantum entanglement detection and characterization are crucial for various quantum information processes. Most existing methods for entanglement detection rely heavily on a complete description of the quantum state, which requires numerous…

Quantum Physics · Physics 2025-04-21 Rui Li , Shikun Zhang , Zheng Qin , Chunxiao Du , Yang Zhou , Zhisong Xiao

We find and investigate the optimal scheme of quantum distributed Gaussian sensing for estimation of the average of independent phase shifts. We show that the ultimate sensitivity is achievable by using an entangled symmetric Gaussian…

Quantum Physics · Physics 2020-04-14 Changhun Oh , Changhyoup Lee , Seok Hyung Lie , Hyunseok Jeong

We investigate the dynamics for a two level atomic system entangled to coherent states using the recently developed mode invisibility technique. Using a quantum 2-level probe, we demonstrate a way to non-destructively measure a number of…

Quantum Physics · Physics 2017-10-04 Paulina Corona-Ugalde , Marvellous Onuma-Kalu , Robert B. Mann