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Quantifying entanglement is an important issue in quantum information theory. Here we consider the entanglement measures through the trace norm in terms of two methods, the modified measure and the extended measure for bipartite states. We…

Quantum Physics · Physics 2023-02-09 Xian Shi , Lin Chen , Yixuan Liang

Quantum computation offers significant potential for accelerating the simulation of molecules and materials through algorithms such as quantum phase estimation (QPE). However, the expected speedup in ground-state energy estimation depends…

Quantum Physics · Physics 2025-06-17 Zhendong Li

An universal approximation technique for analysis of different characteristics of states of composite infinite-dimensional quantum systems is proposed and used to prove general results concerning the properties of correlation and…

Quantum Physics · Physics 2024-11-01 M. E. Shirokov

An iterative random procedure is considered allowing an entanglement purification of a class of multi-mode quantum states. In certain cases, a complete purification may be achieved using only a single signal state preparation. A physical…

Quantum Physics · Physics 2009-11-10 J Clausen , L Knoell , D-G Welsch

We present optimal measuring strategies for the estimation of the entanglement of unknown two-qubit pure states and of the degree of mixing of unknown single-qubit mixed states, of which N identical copies are available. The most general…

Quantum Physics · Physics 2009-10-31 A. Acin , R. Tarrach , G. Vidal

We show that combining randomized measurement protocols with importance sampling allows for characterizing entanglement in significantly larger quantum systems and in a more efficient way than in previous work. A drastic reduction of…

Quantum Physics · Physics 2023-01-26 Aniket Rath , Rick van Bijnen , Andreas Elben , Peter Zoller , Benoît Vermersch

A fundamental task in quantum information is to approximate a pure quantum state in terms of sparse states or, for a bipartite system, states of bounded Schmidt rank. The optimal deterministic approximation in each case is straightforward,…

Quantum Physics · Physics 2026-01-06 Aram W. Harrow , Angus Lowe , Freek Witteveen

Entanglement of pure states of bipartite quantum systems has been shown to have a unique measure in terms of the von Neumann entropy of the reduced states of either of its subsystems. The measure is established under entanglement…

Quantum Physics · Physics 2007-05-23 Garry Bowen , Nilanjana Datta

We demonstrate that local transformations on a composite quantum system can be enhanced in the presence of certain entangled states. These extra states act much like catalysts in a chemical reaction: they allow otherwise impossible local…

Quantum Physics · Physics 2009-01-23 Daniel Jonathan , Martin B. Plenio

Quantum entanglement is a foundational resource in quantum information science, underpinning applications across physics. However, detecting and quantifying entanglement remains a significant challenge. In this article, we introduce a…

Entanglement is the central resource of quantum information processing and the precise characterization of entangled states is a crucial issue for the development of quantum technologies. This leads to the necessity of a precise,…

Quantum entanglement of identical particles is essential in quantum information theory. Yet, its correct determination remains an open issue hindering the general understanding and exploitation of many-particle systems. Operator-based…

Quantum Physics · Physics 2016-03-08 Rosario Lo Franco , Giuseppe Compagno

We determine the resource scaling of machine learning-based quantum state reconstruction methods, in terms of inference and training, for systems of up to four qubits when constrained to pure states. Further, we examine system performance…

Quantum Physics · Physics 2022-01-25 Sanjaya Lohani , Thomas A. Searles , Brian T. Kirby , Ryan T. Glasser

Quantum state tomography serves as a key tool for identifying quantum states generated in quantum computers and simulators, typically involving local operations on individual particles or qubits to enable independent measurements. However,…

Quantum Gases · Physics 2026-03-26 Giacomo Marmorini , Takeshi Fukuhara , Daisuke Yamamoto

We propose a modular quantum computation architecture based on utilizing multipartite entanglement. Each module consists of a small-scale quantum computer comprising data, memory and entangling qubits. Entangling qubits are used to…

Quantum Physics · Physics 2024-12-16 Ferran Riera-Sàbat , Wolfgang Dür

Estimating quantum amplitude, or the overlap between two quantum states, is a fundamental task in quantum computing and underpins numerous quantum algorithms. In this work, we introduce a novel algorithmic framework for quantum amplitude…

Quantum Physics · Physics 2025-02-27 Zhong-Xia Shang , Qi Zhao

Quantum metrology exploits entangled states of particles to improve sensing precision beyond the limit achievable with uncorrelated particles. All previous methods required detection noise levels below this standard quantum limit to realize…

Quantum Physics · Physics 2020-12-09 O. Hosten , R. Krishnakumar , N. J. Engelsen , M. A. Kasevich

The ability to generate bipartite entanglement in quantum computing technologies is widely regarded as pivotal. However, the role of genuinely multipartite entanglement is much less understood than bipartite entanglement, particularly in…

Quantum Physics · Physics 2025-02-24 Gopal Chandra Santra , Sudipto Singha Roy , Daniel J. Egger , Philipp Hauke

The ability to selectively measure, initialize, and reuse qubits during a quantum circuit enables a mapping of the spatial structure of certain tensor-network states onto the dynamics of quantum circuits, thereby achieving dramatic resource…

Entanglement plays a fundamental role in quantum physics and information processing. Here, we develop an unbiased estimator for mixed-state entanglement in the few-shot scenario and directly estimate it using random unitary evolution in a…

Quantum Physics · Physics 2024-07-09 Gong-Chu Li , Lei Chen , Si-Qi Zhang , Xu-Song Hong , You Zhou , Geng Chen , Chuan-Feng Li , Guang-Can Guo