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We investigate the generation of the entanglement in a cavity magnomechanical system, which consists of three modes: a magnon mode, a microwave cavity mode and a mechanical vibration mode, the couplings of the magnon-photon and the…

Quantum Physics · Physics 2022-09-28 Ming-Song Ding , Ying Shi , Yu-jie Liu , Li Zheng

Entanglement is the crucial ingredient of quantum many-body physics, and characterizing and quantifying entanglement in closed system dynamics of quantum simulators is an outstanding challenge in today's era of intermediate scale quantum…

Quantum Physics · Physics 2021-08-31 Christian Kokail , Rick van Bijnen , Andreas Elben , Benoît Vermersch , Peter Zoller

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

We experimentally demonstrate a general criterion to identify entangled states useful for the estimation of an unknown phase shift with a sensitivity higher than the shot-noise limit. We show how to exploit this entanglement on the examples…

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…

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

We investigate the entanglement transfer from a bipartite continuous-variable (CV) system to a pair of localized qubits assuming that each CV mode couples to one qubit via the off-resonance Jaynes-Cummings interaction with different…

Quantum Physics · Physics 2009-11-13 Federico Casagrande , Alfredo Lulli , Matteo G. A. Paris

We develop a scheme to prepare a macroscopic maximally entangled state (MMES) between two atomic ensembles using adaptive quantum nondemolition (QND) measurements. The quantum state of the system is evolved using a sequence of QND…

Quantum Physics · Physics 2023-09-15 Manish Chaudhary , Ebubechukwu O. Ilo-Okeke , Valentin Ivannikov , Tim Byrnes

Quantum entanglement is a particularly useful characterization of topological orders which lack conventional order parameters. In this work, we study the entanglement in topologically ordered states between two arbitrary spatial regions,…

Strongly Correlated Electrons · Physics 2023-08-01 Chao Yin , Shang Liu

The verification of quantum entanglement is essential for quality control in quantum communication. In this work, we propose an efficient protocol to directly verify the two-qubit entanglement of a known target state through a single…

Quantum Physics · Physics 2026-04-22 Ricardo Rodriguez , Nam Nguyen , Elizabeth Behrman , Andrew C. Y. Li , James Steck

We present an experimentally feasible and efficient method for detecting entangled states with measurements that extend naturally to a tomographically complete set. Our detection criterion is based on measurements from subsets of a quantum…

Quantum Physics · Physics 2019-01-30 Joonwoo Bae , Beatrix C. Hiesmayr , Daniel McNulty

Addition of single photons to two-mode-squeezed-vacuum states has the effect of distilling quantum entanglement, and, when deployed in quantum key distribution, should lead also to an increase in the secret key rate. However, the extraction…

Quantum Physics · Physics 2025-07-25 Hao Jeng , Ping Koy Lam , Syed M. Assad

In multi-parameter quantum metrology, the resource of entanglement can lead to an increase in efficiency of the estimation process. Entanglement can be used in the state preparation stage, or the measurement stage, or both, to harness this…

Quantum Physics · Physics 2025-10-01 Aritra Das , Lorcán O. Conlon , Jun Suzuki , Simon K. Yung , Ping K. Lam , Syed M. Assad

Experimental determination of entanglement is important not only to characterize the state and use it in quantum information, but also in understanding complicated phenomena such as phase transitions. In this paper we show that in many…

Quantum Physics · Physics 2016-01-20 Gaurav Chaudhary , V. Ravishankar

We introduce a general model for a network of quantum sensors, and we use this model to consider the question: When can entanglement between the sensors, and/or global measurements, enhance the precision with which the network can measure a…

Quantum Physics · Physics 2018-02-28 Timothy J. Proctor , Paul A. Knott , Jacob A. Dunningham

Quantum entanglement and Einstein-Podolsky-Rosen (EPR) steering are valuable resources in quantum information processing. How to enhance the quantum entanglement and EPR steering of coupled optomechanical systems with a weak squeezed vacuum…

Quantum Physics · Physics 2023-10-24 Shao-Xiong Wu , Cheng-Hua Bai , Gang Li , Chang-shui Yu , Tiancai Zhang

With the advance of quantum information technology, the question of how to most efficiently test quantum circuits is becoming of increasing relevance. Here we introduce the statistics of lengths of measurement sequences that allows one to…

Quantum Physics · Physics 2022-10-27 N. Milazzo , D. Braun , O. Giraud

Two-mode squeezing is a fascinating example of quantum entanglement manifested in cross-correlations of incompatible observables between two subsystems. At the same time, these subsystems themselves may contain no quantum signatures in…

Given a quantum system $S$ entangled with another system $I$, the entanglement testing problem arises, prompting the identification of the system $S$ within a set of $m \ge 2$ identical systems. This scenario serves as a model for the…

Quantum Physics · Physics 2023-12-27 Pengcheng Liao , Quntao Zhuang

We propose Gaussian quantum illumination(QI) protocol exploiting asymmetrically squeezed two-mode(ASTM) state that is generated by applying single-mode squeezing operations on each mode of an initial two-mode squeezed vacuum(TMSV) state, in…

Quantum Physics · Physics 2021-07-21 Yonggi Jo , Taek Jeong , Junghyun Kim , Duk Y. Kim , Yong Sup Ihn , Zaeill Kim , Su-Yong Lee