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Entanglement is at the heart of most quantum information tasks, and therefore considerable effort has been made to find methods of deciding the entanglement content of a given bipartite quantum state. Here, we prove a fundamental limitation…

Quantum Physics · Physics 2016-06-15 Claudio Carmeli , Teiko Heinosaari , Antti Karlsson , Jussi Schultz , Alessandro Toigo

It is generally believed that entanglement is essential for quantum computing. We present here a few simple examples in which quantum computing without entanglement is better than anything classically achievable, in terms of the reliability…

Quantum Physics · Physics 2007-05-23 Eli Biham , Gilles Brassard , Dan Kenigsberg , Tal Mor

We derive a general framework to identify genuinely multipartite entangled mixed quantum states in arbitrary-dimensional systems and show in exemplary cases that the constructed criteria are stronger than those previously known. Our…

Quantum Physics · Physics 2013-05-29 Marcus Huber , Florian Mintert , Andreas Gabriel , Beatrix C. Hiesmayr

An outstanding problem in quantum computing is the calculation of entanglement, for which no closed-form algorithm exists. Here we solve that problem, and demonstrate the utility of a quantum neural computer, by showing, in simulation, that…

Quantum Physics · Physics 2007-05-23 E. C. Behrman , V. Chandrashekar , Z. Wang , C. K. Belur , J. E. Steck , S. R. Skinner

This thesis focuses on the experimental creation and detection of a variety of quantum correlations using nuclear magnetic resonance hardware. Quantum entanglement, being most common and counter-intuitive, is one of the main type considered…

Quantum Physics · Physics 2019-05-16 Amandeep Singh

Separability problem is a long-standing tough issue in quantum information theory. In this paper, we propose a general method to detect entanglement via arbitrary measurement $\boldsymbol{X}$, by which several novel criteria are…

Quantum Physics · Physics 2022-08-18 Ma-Cheng Yang , Cong-Feng Qiao

In quantum information and computation, the generation of entanglement through unitary gates remains a significant and active area of research. However, there are states termed as absolutely separable, from which entanglement cannot be…

Quantum Physics · Physics 2026-02-13 Bivas Mallick , Saheli Mukherjee , Nirman Ganguly , A. S. Majumdar

There has been a surge of progress in recent years in developing algorithms for testing and learning quantum states that achieve optimal copy complexity. Unfortunately, they require the use of entangled measurements across many copies of…

Quantum Physics · Physics 2020-04-20 Sebastien Bubeck , Sitan Chen , Jerry Li

We introduce a sequence of numerical tests that can determine the entanglement or separability of a state even when there is not enough information to completely determine its density matrix. Given partial information about the state in the…

Quantum Physics · Physics 2012-12-14 Federico M. Spedalieri

The separability detecting problem of mixed states is one of the fundamental problems in quantum information theory. In the last 20 years, almost all methods are based on the sufficient or necessary conditions for entanglement. However, in…

Quantum Physics · Physics 2020-07-15 Ying Li , Guyan Ni

Multipartite entanglement detection is crucial for the develop of quantum information science and quantum computation, communication, simulation and metrology tasks. In contrast to experiments, where several handreds of qubits have been…

Quantum Physics · Physics 2024-11-06 Xiao-yu Chen

Entanglement detection is essential in quantum information science and quantum many-body physics. It has been proved that entanglement exists almost surely for a random quantum state, while the realizations of effective entanglement…

Quantum Physics · Physics 2022-12-02 Pengyu Liu , Zhenhuan Liu , Shu Chen , Xiongfeng Ma

We propose in this work a practical approach to address the longstanding and challenging problem of quantum separability, leveraging the correlation matrices of generic observables. General separability conditions are obtained by dint of…

Quantum Physics · Physics 2025-05-07 Ma-Cheng Yang , Cong-Feng Qiao

In recent years considerable progress has been made towards developing a general theory of quantum entanglement. In particular, criteria to decide whether a given quantum state is entangled are of high theoretical and practical interest.…

Quantum Physics · Physics 2025-01-27 Shruti Aggarwal

In the past decades, quantum entanglement has been recognized to be the basic resource in quantum information theory. A fundamental need is then the understanding its qualification and its quantification: Is the quantum state entangled, and…

Quantum Physics · Physics 2013-02-20 Szilárd Szalay

We shed new light on entanglement measures in multipartite quantum systems by taking a computational-complexity approach toward quantifying quantum entanglement with two familiar notions--approximability and distinguishability. Built upon…

Quantum Physics · Physics 2007-05-23 Tomoyuki Yamakami

The detection of multipartite entanglement in arbitrary dimensional systems is investigated. We derive useful $k$-separability criteria of mixed $n$-partite ($n\geq 3$) quantum states to detect $k$-nonseparable $n$-partite quantum states.…

Quantum Physics · Physics 2013-01-17 Ting Gao , Yan Hong

It is pointed out that separability problem for arbitrary multi-partite states can be fully solved by a finite size, elementary recursive algorithm. In the worse case scenario, the underlying numerical procedure, may grow doubly…

Quantum Physics · Physics 2007-05-23 Piotr Badziag , Pawel Horodecki , Ryszard Horodecki

Classifying states as entangled or separable is a highly challenging task, while it is also one of the foundations of quantum information processing theory. This task is higly nontrivial even for relatively simple cases, such as two-qutrit…

Quantum Physics · Physics 2022-11-08 Marcin Wieśniak

We introduce an experimental procedure for the detection of quantum entanglement of an unknown quantum state with as few measurements as possible. The method requires neither a priori knowledge of the state nor a shared reference frame…