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Entanglement is considered to be one of the most profound features of quantum mechanics. An entangled state of a system consisting of two subsystems cannot be described as a product of the quantum states of the two subsystems. In this sense…

Quantum Physics · Physics 2009-11-07 Brian Julsgaard , Alexander Kozhekin , Eugene S. Polzik

Genuine multipartite entanglement is arguably the most valuable form of entanglement in the multipartite case, with applications, for instance, in quantum metrology. In order to detect that form of entanglement in multipartite quantum…

Quantum Physics · Physics 2026-04-07 Jakub Szczepaniak , Owidiusz Makuta , Remigiusz Augusiak

Entanglement witnesses (EW) allow the detection of entanglement in a quantum system, from the measurement of some few observables. They do not require the complete determination of the quantum state, which is regarded as a main advantage.…

Quantum Physics · Physics 2012-02-02 J. G. Filgueiras , T. O. Maciel , R. E. Auccaise , R. O. Vianna , R. S. Sarthour , I. S. Oliveira

Entanglement witnesses are invaluable for efficient quantum entanglement certification without the need for expensive quantum state tomography. Yet, standard entanglement witnessing requires multiple measurements and its bounds can be…

Quantum Physics · Physics 2017-03-22 Farid Shahandeh , Martin Ringbauer , Juan C. Loredo , Timothy C. Ralph

In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

This paper points out the importance of the quantum nature of the gravitational interaction with matter in a linearized theory of quantum gravity induced entanglement of masses (QGEM). We will show how the quantum interaction entangles the…

General Relativity and Quantum Cosmology · Physics 2022-06-03 Sougato Bose , Anupam Mazumdar , Martine Schut , Marko Toroš

In our previous work, we have explored quantum gravity induced entanglement of mass (QGEM) in curved spacetime, observing entanglement formation between particles moving along geodesics in a Schwarzschild spacetime background. We find that…

General Relativity and Quantum Cosmology · Physics 2024-05-21 Chi Zhang , Fu-Wen Shu

Entanglement is a key resource to demonstrate quantum advantage over classical strategies. Entanglement in quantum states is one of the most well-explored areas in quantum physics. However, a rigorous approach to understanding and detecting…

Quantum Physics · Physics 2025-02-12 Shubhayan Sarkar

In order to detect the quantum nature of gravity, the quantum gravity induced entanglement of masses(QGEM) has been proposed both in flat and curved spacetime. In this paper we propose an analogous QGEM protocol using photons produced in…

General Relativity and Quantum Cosmology · Physics 2025-11-27 Chi Zhang

We propose a set of linear quantum entanglement witnesses constituted by local quantum-mechanical observables with each two possible measurement outcomes. These witnesses detect all the entangled resources which give rise to a better…

Quantum Physics · Physics 2012-05-04 Ming-Jing Zhao , Shao-Ming Fei , Xianqing Li-Jost

Quantum entanglement is a form of correlation between quantum particles that cannot be increased via local operations and classical communication. It has therefore been proposed that an increment of quantum entanglement between probes that…

Quantum Physics · Physics 2021-06-23 Soham Pal , Priya Batra , Tanjung Krisnanda , Tomasz Paterek , T. S. Mahesh

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…

Projective measurements are a powerful tool for manipulating quantum states. In particular, a set of qubits can be entangled by measurement of a joint property such as qubit parity. These joint measurements do not require a direct…

Quantum computers have the potential to solve certain interesting problems significantly faster than classical computers. To exploit the power of a quantum computation it is necessary to perform inter-qubit operations and generate entangled…

Mesoscale and Nanoscale Physics · Physics 2013-04-09 Michael D. Shulman , Oliver E. Dial , Shannon P. Harvey , Hendrik Bluhm , Vladimir Umansky , Amir Yacoby

We develop a quantum field-theoretic model of gravitationally induced entanglement (GIE) between two massive objects in spatial superposition. The masses are described as excitations of a scalar field in an external harmonic potential,…

Quantum Physics · Physics 2025-04-03 Jackson Yant , Miles Blencowe

One of the outstanding questions in modern physics is how to test whether gravity is classical or quantum in a laboratory. Recently there has been a proposal to test the quantum nature of gravity by creating quantum superpositions of two…

Quantum Physics · Physics 2023-11-14 Fabian Gunnink , Anupam Mazumdar , Martine Schut , Marko Toroš

Entanglement is a fundamental resource that allows quantum sensors to surpass the standard quantum limit set by the quantum collapse of independent atoms. Collective cavity-QED systems have succeeded in generating large amounts of directly…

Quantum Physics · Physics 2023-03-30 Graham P. Greve , Chengyi Luo , Baochen Wu , James K. Thompson

We investigate the evolution of entanglement in multiple-quantum (MQ) NMR experiments in crystals with pairs of close nuclear spins-1/2. The initial thermodynamic equilibrium state of the system in a strong external magnetic field evolves…

Quantum Physics · Physics 2009-11-13 E. B. Fel'dman , A. N. Pyrkov

Entanglement plays a crucial role in quantum information science and many-body physics, yet quantifying it in mixed quantum many-body systems has remained a notoriously difficult problem. Here, we introduce families of quantitative…

Quantum Physics · Physics 2025-07-21 Poetri Sonya Tarabunga , Tobias Haug

We investigate the interplay between quantum theory and gravity by exploring gravitational lensing and Einstein ring images in a weak gravitational field induced by a mass source in spatial quantum superposition. We analyze a quantum…

General Relativity and Quantum Cosmology · Physics 2025-03-05 Youka Kaku , Yasusada Nambu