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We introduce an entanglement-depth criterion optimized for planar quantum squeezed (PQS) states. It is connected with the sensitivity of such states for estimating an arbitrary, not necessarily small phase. We compare numerically our…

The states of a three-mode bosonic system with the restricted Hilbert space are discussed in the context of quantum entanglement and squeezing of quantum fluctuations. The states exhibiting non-zero tripartite entanglement are considered.…

Quantum Physics · Physics 2026-03-06 Joanna K. Kalaga , Jan Perina

We analyze the collective spin noise in interacting spin systems. General expressions are derived for the short time behaviour of spin systems with general spin-spin interactions, and we suggest optimum experimental conditions for the…

Quantum Physics · Physics 2009-11-07 Xiaoguang Wang , Anders S. Sorensen , Klaus Molmer

We investigate the relation between the amount of entanglement localized on a chosen subsystem of a multi-qubit system via local measurements on the rest of the system, and the bipartite entanglement that is lost during this measurement…

Quantum Physics · Physics 2026-05-11 Jithin G. Krishnan , Harikrishnan K. J. , Amit Kumar Pal

In this article, we investigate the entanglement evolution of three-qubit states in the presence of a spin chain environment. Utilizing negativity as a metric for entanglement assessment, we focus on the GHZ, W, and W_zeta quantum states as…

Quantum Physics · Physics 2025-02-11 Seyed Mohsen Moosavi Khansari , Fazlollah Kazemi Hasanvand

These two accompanying papers treat two mode entanglement for systems of identical massive bosons and the relationship to spin squeezing and other quantum correlation effects. Entanglement is a key quantum feature of composite systems where…

Quantum Physics · Physics 2016-01-07 Bryan Dalton , John Goold , Barry Garraway , Margaret Reid

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…

We report on the experimental observation and characterization of a six-photon entangled Dicke state. We obtain a fidelity as high as 0.654$\pm$0.024 and prove genuine six-photon entanglement by, amongst others, a two-setting witness…

The structure and quantification of entanglement in the W-class states are investigated under physically motivated transformations that induce mixed-state dynamics. A rigorous condition is established linking global separability to the…

Quantum Physics · Physics 2025-12-17 Reza Hamzehofi

These two accompanying papers treat two mode entanglement for systems of identical massive bosons and the relationship to spin squeezing and other quantum correlation effects. Entanglement is a key quantum feature of composite systems where…

Quantum Physics · Physics 2016-06-01 Bryan Dalton , John Goold , Barry Garraway , Margaret Reid

A new formulation called as entanglement measure for simplification, is presented to characterize genuine tripartite entanglement of $(2\times 2\times n)-$dimensional quantum pure states. The formulation shows that the genuine tripartite…

Quantum Physics · Physics 2008-12-05 Chang-shui Yu , He-shan Song , Hai-tao Cui

Entanglement is one of the key resources required for quantum computation, so experimentally creating and measuring entangled states is of crucial importance in the various physical implementations of a quantum computer. In superconducting…

Spin-squeezed states are metrologically useful quantum states where entanglement allows for enhanced sensing with respect to the standard quantum limit. Key challenges include the efficient preparation of spin-squeezed states and the…

Quantum Physics · Physics 2025-12-11 Stefano Giaccari , Giulia Dellea , Marco G. Genoni , Gianluca Bertaina

We construct a set of criteria detecting genuine multipartite entanglement in arbitrary dimensional multipartite systems. These criteria are optimally suited for detecting multipartite entanglement in n-qubit Dicke states with…

Quantum Physics · Physics 2011-10-14 Marcus Huber , Paul Erker , Hans Schimpf , Andreas Gabriel , Beatrix C. Hiesmayr

Quantum entanglement is essential to the development of quantum computation, communications, and technology. The controlled SWAP test, widely used for state comparison, can be adapted to an efficient and useful test for entanglement of a…

Quantum Physics · Physics 2022-01-12 Steph Foulds , Viv Kendon , Tim Spiller

We propose a strategy to generate a many-body entangled state in a collection of randomly placed, dipolarly coupled electronic spins in the solid state. By using coherent control to restrict the evolution into a suitable collective…

Quantum Physics · Physics 2009-09-12 Paola Cappellaro , Mikhail D. Lukin

We study genuine entanglement among $3$-qubits undergoing through a noisy process including dissipation, squeezing and decoherence. We obtain a general solution and analyze the asymptotic quantum states. It turns out that most of these…

Quantum Physics · Physics 2024-07-08 Mazhar Ali

We prove that the vast majority of symmetric states of qubits can be decomposed in a unique way into a superposition of spin 1/2 coherent states. For the case of two qubits, the proposed decomposition reproduces the Schmidt decomposition…

Quantum Physics · Physics 2015-06-25 A. Mandilara , T. Coudreau , A. Keller , P. Milman

The n-qubit real equally weighted states are employed in some quantum algorithms including Deutsch-Jozsa, Grover, Simon, and so on. We qualitatively investigate the entanglement properties of n-qubit real equally weighted states. Firstly,…

Quantum Physics · Physics 2012-07-12 Ri Qu , Yanru Bao

Spin squeezing in collective atomic ensembles enables quantum-enhanced metrology by reducing noise below the standard quantum limit through nonlinear interactions. Extending the one-axis and two-axis twisting paradigms of Kitagawa and Ueda,…

Quantum Physics · Physics 2026-01-01 Chon-Fai Kam