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In this paper, we investigate the hierarchical structure of the $n$-partite quantum states. We present a whole set of hierarchical quantifications as a method of characterizing quantum states, which go beyond genuine multipartite…

Quantum Physics · Physics 2025-03-26 Hui Li , Ting Gao , Fengli Yan

If only limited control over a multiparticle quantum system is available, a viable method to characterize correlations is to perform random measurements and consider the moments of the resulting probability distribution. We present…

Quantum Physics · Physics 2021-04-23 Satoya Imai , Nikolai Wyderka , Andreas Ketterer , Otfried Gühne

To address the outstanding task of detecting entanglement in large quantum systems, entanglement witnesses have emerged, addressing the separable nature of a state. Yet optimizing witnesses, or accessing them experimentally, often remains a…

Quantum metrology takes advantage of nonclassical resources such as entanglement to achieve a sensitivity level below the standard quantum limit. To date, almost all quantum-metrology demonstrations are restricted to improving the…

Quantum Physics · Physics 2020-04-22 Yi Xia , Wei Li , William Clark , Darlene Hart , Quntao Zhuang , Zheshen Zhang

In this letter we investigate the possibility of observing macroscopic entanglement, considering realistic factors such as decoherence, particle losses, and measurements of limited precision (coarse-grained collective measurements). This…

Quantum Physics · Physics 2025-02-24 Martina Gisti , Miguel Gallego , Borivoje Dakić

We investigate the structural aspects of genuine multipartite entanglement in Gaussian states of continuous variable systems. Generalizing the results of [Adesso & Illuminati, Phys. Rev. Lett. 99, 150501 (2007)], we analyze whether the…

Quantum Physics · Physics 2008-10-14 Gerardo Adesso , Fabrizio Illuminati

We derive a family of necessary separability criteria for finite-dimensional systems based on inequalities for variances of observables. We show that every pure bipartite entangled state violates some of these inequalities. Furthermore, a…

Quantum Physics · Physics 2016-09-08 Otfried Guehne

Quantum correlations are at the core of the power of quantum information and are necessary to reach a quantum computational advantage. In the context of continuous-variable quantum systems, another necessary ressource for quantum advantages…

Quantum Physics · Physics 2024-07-26 Carlos E. Lopetegui , Mathieu Isoard , Nicolas Treps , Mattia Walschaers

Genuine multipartite entanglement is crucial for quantum information and related technologies but quantifying it has been a long-standing challenge. Most proposed measures do not meet the ``genuine'' requirement, making them unsuitable for…

Quantum Physics · Physics 2024-06-25 Songbo Xie , Daniel Younis , Yuhan Mei , Joseph H. Eberly

The lack of methods to experimentally detect and quantify entanglement in quantum matter impedes our ability to identify materials hosting highly entangled phases, such as quantum spin liquids. We thus investigate the feasibility of using…

We show how to verify the metrological usefulness of quantum states based on the expectation values of an arbitrarily chosen set of observables. In particular, we estimate the quantum Fisher information as a figure of merit of metrological…

Quantum Physics · Physics 2017-04-25 Iagoba Apellaniz , Matthias Kleinmann , Otfried Gühne , Geza Toth

Learning physical properties of high-dimensional states is crucial for developing quantum technologies but usually consumes an exceedingly large number of samples which are difficult to afford in practice. In this Letter, we use the…

Quantum Physics · Physics 2024-07-29 Da-Jian Zhang , D. M. Tong

Measuring entanglement is a demanding task in the field of quantum computation and quantum information theory. Recently, some authors experimentally demonstrated an embedding quantum simulator, using it to efficiently measure two-qubit…

Quantum Physics · Physics 2018-11-01 Saeed Haddadi , Mohammad Bohloul

It is a specific type of quantum correlated state that achieves optimal precision in parameterestimation under unitary encoding. We consider the potential experimental limitation on probe entanglement, and find a relation between achievable…

Quantum Physics · Physics 2026-01-06 Debarupa Saha , Ujjwal Sen

Negativity is regarded as an important measure of entanglement in quantum information theory. In contrast to other measures of entanglement, it is easily computable for bipartite states in arbitrary dimensions. In this paper, based on the…

Quantum Physics · Physics 2010-04-30 Yong-Cheng Ou , Mark S. Byrd

Monitored quantum systems evolve along stochastic trajectories correlated with the observer's knowledge of the system's state. Under such dynamics, certain quantum resources like entanglement may depend on the observer's state of knowledge.…

Quantum Physics · Physics 2024-09-04 Christian Carisch , Oded Zilberberg , Alessandro Romito

Multipartite entanglement is a crucial resource for a wide range of quantum information processing tasks, including quantum metrology, quantum computing, and quantum communication. The verification of multipartite entanglement, along with…

Quantum Physics · Physics 2024-12-24 Kai Wu , Zhihua Chen , Zhen-Peng Xu , Zhihao Ma , Shao-Ming Fei

We use quantum entanglement witnesses derived from Gaussian operators to study the separable criteria of continuous variable states. We transform the validity of a Gaussian witness to a Bosonic Gaussian channel problem. It follows that the…

Quantum Physics · Physics 2022-08-29 Xiao-yu Chen , Maoke Miao , Rui Yin , Jiantao Yuan

The resources needed to conventionally characterize a quantum system are overwhelmingly large for high- dimensional systems. This obstacle may be overcome by abandoning traditional cornerstones of quantum measurement, such as general…

Quantum Physics · Physics 2016-05-17 Gregory A. Howland , Samuel H. Knarr , James Schneeloch , Daniel J. Lum , John C. Howell

We introduce the challenges of multi-party quantum entanglement and explain a recent success in learning to take its measure. Given the widely accepted reputation of entanglement as a counter-intuitive feature of quantum theory, we first…

Quantum Physics · Physics 2023-11-21 Songbo Xie , J. H. Eberly