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We explore the subtle relationships between partial separability and entanglement of subsystems in multiqubit quantum states and give experimentally accessible conditions that distinguish between various classes and levels of partial…

Quantum Physics · Physics 2008-09-03 Michael Seevinck , Jos Uffink

We study the detection of continuous-variable entanglement, for which most of the existing methods designed so far require a full specification of the devices, and we present protocols for entanglement detection in a scenario where the…

Quantum Physics · Physics 2021-05-19 Paolo Abiuso , Stefan Bäuml , Daniel Cavalcanti , Antonio Acín

We qualify the entanglement of arbitrary mixed states of bipartite quantum systems by comparing global and marginal mixednesses quantified by different entropic measures. For systems of two qubits we discriminate the class of maximally…

Quantum Physics · Physics 2007-05-23 Gerardo Adesso , Fabrizio Illuminati , Silvio De Siena

We generalize the notion of joint measurability to continuous variable systems by extending a recently introduced compression algorithm of quantum measurements to this realm. The extension results in a property that asks for the minimal…

Quantum Physics · Physics 2026-03-03 Pauli Jokinen , Sophie Egelhaaf , Juha-Pekka Pellonpää , Roope Uola

In the rapidly evolving field of quantum computing, optimizing quantum circuits for specific tasks is crucial for enhancing performance and efficiency. More recently, quantum sensing has become a distinct and rapidly growing branch of…

Quantum Physics · Physics 2025-09-01 Laxmisha Ashok Attisara , Sathish Kumar

Among the many facets of quantum correlations, bound entanglement has remained one the most enigmatic phenomena, despite the fact that it was discovered in the early days of quantum information. Even its detection has proven to be…

Quantum Physics · Physics 2016-09-07 Gael Sentís , Christopher Eltschka , Jens Siewert

Necessary and sufficient observable conditions for the nonnegativity of all partial transpositions of multi-mode quantum states are derived. The result is a hierarchy of inequalities for minors in terms of moments of the given state.…

Quantum Physics · Physics 2009-11-13 E. Shchukin , W. Vogel

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

Quantum entanglement is a key resource in quantum technology, and its quantification is a vital task in the current Noisy Intermediate-Scale Quantum (NISQ) era. This paper combines hybrid quantum-classical computation and quasi-probability…

Quantum Physics · Physics 2023-10-16 Kun Wang , Zhixin Song , Xuanqiang Zhao , Zihe Wang , Xin Wang

Distributed quantum sensing leverages quantum correlations among multiple sensors to enhance the precision of parameter estimation beyond classical limits. Most existing approaches target phase estimation and rely on a shared phase…

Quantum Physics · Physics 2026-02-04 Piotr T. Grochowski , Matteo Fadel , Radim Filip

We ask whether the optimal probe is entangled, and if so, what is its character and amount, for estimating the noise parameter of a large class of local quantum encoding processes that we refer to as vector encoding, examples of which…

Quantum Physics · Physics 2026-04-23 Shuva Mondal , Priya Ghosh , Ujjwal Sen

Given a real-valued phase-space function, it is a nontrivial task to determine whether it corresponds to a Wigner distribution for a physically acceptable quantum state. This topic has been of fundamental interest for long, and in a modern…

Quantum Physics · Physics 2009-11-13 Hyunchul Nha

Localizability of entanglement in fully inseparable states is a key ingredient of assisted quantum information protocols as well as measurement-based models of quantum computing. We investigate the existence of fully inseparable states with…

Quantum Physics · Physics 2017-10-31 M. Mičuda , D. Koutný , M. Miková , I. Straka , M. Ježek , L. Mišta

The states in the three-qubit GHZ SLOCC class can exhibit diverse entanglement patterns, as they may have no entanglement in any reduced subsystems, or show entanglement across one, two, or all three bipartite cuts. Significant research has…

We study the evolution of bipartite entangled quasi-Bell states in a strongly coupled qubit-oscillator system in the presence of a static bias, and extend it to the ultra-strong coupling regime. Using the adiabatic approximation the reduced…

Quantum Physics · Physics 2015-06-03 R. Chakrabarti , B. Virgin Jenisha

Characterizing and quantifying quantum correlations in states of many-particle systems is at the core of a full understanding of phase transitions in matter. In this work, we continue our investigation of the notion of generalized…

Quantum Physics · Physics 2009-11-10 Rolando Somma , Gerardo Ortiz , Howard Barnum , Emanuel Knill , Lorenza Viola

We consider the problem of determining the spatial phase profile of a single-mode electromagnetic field. Our attention is on input states that are a statistical mixture of displaced and squeezed number states, a superset of Gaussian states.…

Optics · Physics 2024-07-09 Jacob Trzaska , Amit Ashok

The entanglement entropy of the ground state of a quantum lattice model with local interactions usually satisfies an area law. However, in 1D systems some violations may appear in inhomogeneous systems or in random systems. In our…

Quantum Physics · Physics 2018-05-08 Giovanni Ramírez

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 have studied entanglement entropy and Husimi $Q$ distribution as a tool to explore chaos in the quantum two-photon Dicke model. With the increase of the energy of system, the linear entanglement entropy of coherent state prepared in the…

Quantum Physics · Physics 2019-08-21 Shangyun Wang , Songbai Chen , Jiliang Jing