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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

Standard procedures for entanglement detection assume that experimenters can exactly implement specific quantum measurements. Here, we depart from such idealizations and investigate, in both theory and experiment, the detection of genuine…

Quantum Physics · Physics 2024-10-10 Huan Cao , Simon Morelli , Lee A. Rozema , Chao Zhang , Armin Tavakoli , Philip Walther

The characterization of high-dimensional entanglement plays a crucial role in the field of quantum information science. Conventional entanglement criteria measuring coherent superpositions of multiple basis states face experimental…

Quantum Physics · Physics 2026-02-12 Jin-Min Liang , Shuheng Liu , Shao-Ming Fei , Qiongyi He

Quantum entangled states of light are essential for quantum technologies and fundamental tests of physics. While quantum information science has relied on systems with entanglement in 2D degrees of freedom, e.g. quantum bits with…

Optics · Physics 2017-10-06 Matthew Reichert , Hugo Defienne , Jason W. Fleischer

Entanglement witnesses are one of the most effective methods to detect entanglement. It is known that nonlinear entanglement witnesses provide better entanglement detection than their linear counterparts, in that the former detect a…

Quantum Physics · Physics 2025-12-25 Kornikar Sen , Chirag Srivastava , Ujjwal Sen

Entangled coherent states are shown to emerge, with high fidelity, when mixing coherent and squeezed vacuum states of light on a beam-splitter. These maximally entangled states, where photons bunch at the exit of a beamsplitter, are…

Quantum Physics · Physics 2019-05-31 Yonatan Israel , Lior Cohen , Xin-Bing Song , Jaewoo Joo , Hagai S. Eisenberg , Yaron Silberberg

Entanglement is an important resource that allows quantum technologies to go beyond the classically possible. There are many ways quantum systems can be entangled, ranging from the archetypal two-qubit case to more exotic scenarios of…

Quantum Physics · Physics 2019-06-27 Nicolai Friis , Giuseppe Vitagliano , Mehul Malik , Marcus Huber

We present a novel method to perform quantum state tomography for many-particle systems which are particularly suitable for estimating states in lattice systems such as of ultra-cold atoms in optical lattices. We show that the need for…

Quantum Physics · Physics 2015-06-04 M. Ohliger , V. Nesme , J. Eisert

Motivated by the Peres-Horodecki criterion and the realignment criterion we develop a more powerful method to identify entangled states for any bipartite system through a universal construction of the witness operator. The method also gives…

Quantum Physics · Physics 2009-11-10 Kai Chen , Ling-An Wu

We study the quantum separability problem by using general symmetric informationally complete measurements and present separability criteria for both $d$-dimensional bipartite and multipartite systems. The criterion for bipartite quantum…

Quantum Physics · Physics 2015-06-09 Bin Chen , Tao Li , Shao-Ming Fei

There exists, in general, a convex set of quantum state estimators that maximize the likelihood for informationally incomplete data. We propose an estimation scheme, catered to measurement data of this kind, to search for the exact…

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

A 3-setting Bell-type inequality enforced by the indeterminacy relation of complementary local observables is proposed as an experimental test of the 2-qubit entanglement. The proposed inequality has an advantage of being a sufficient and…

Quantum Physics · Physics 2016-11-15 Sixia Yu , Jian-Wei Pan , Zeng-Bing Chen , Yong-De Zhang

Detecting the entanglement structure, such as intactness and depth, of an n-qubit state is important for understanding the imperfectness of the state preparation in experiments. However, identifying such structure usually requires an…

Quantum Physics · Physics 2020-12-15 Changbo Chen , Changliang Ren , Hongqing Lin , He Lu

A typical concept in quantum state analysis is based on the idea that states in the vicinity of some pure entangled state share the same properties; implying that states with a high fidelity must be entangled. States whose entanglement can…

Quantum Physics · Physics 2021-04-12 Otfried Gühne , Yuanyuan Mao , Xiao-Dong Yu

Understanding the distribution of quantum entanglement over many parties is a fundamental challenge of quantum physics and is of practical relevance for several applications in the field of quantum information. Here we use methods from…

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

A measurement scheme of atomic qubits pinned at given positions is studied by analyzing the interference pattern obtained when they emit photons spontaneously. In the case of two qubits, a well-known relation is revisited, in which the…

Quantum Physics · Physics 2015-05-18 Jun Suzuki , Christian Miniatura , Kae Nemoto

Many experiments in quantum information aim at creating multi-partite entangled states. Quantifying the amount of entanglement that was actually generated can, in principle, be accomplished using full-state tomography. This method requires…

Quantum Physics · Physics 2015-05-13 Harald Wunderlich , Martin B. Plenio

The certification of entanglement dimensionality is of great importance in characterizing quantum systems. Recently, it is pointed out that quantum correlation of high-dimensional states can be simulated with a sequence of lower-dimensional…

Quantum Physics · Physics 2020-06-22 Yu Guo , Bai-Chu Yu , Xiao-Min Hu , Bi-Heng Liu , Yu-Chun Wu , Yun-Feng Huang , Chuan-Feng Li , Guang-Can Guo