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We show that two parties far apart can use shared entangled states and classical communication to align their coordinate systems with a very high fidelity. Moreover compared with previous methods proposed for such a task, i.e. sending…

Quantum Physics · Physics 2017-08-16 F. Rezazadeh , A. Mani , V. Karimipour

Quantum state tomography is a technique in quantum information science used to reconstruct the density matrix of an unknown quantum state, providing complete information about the quantum state. It is of significant importance in fields…

Quantum Physics · Physics 2025-07-23 Wenlong Zhao , Da Zhang , Huili Zhang , Haifeng Yu , Zhang-qi Yin

The quantum fisher information and quantum correlation parameters are employed to study the application of non-classical light to the problem of parameter estimation. It is shown that the optimal measurement sensitivity of a quantum state…

Quantum Physics · Physics 2015-01-09 Jaspreet Sahota , Nicolás Quesada

We use a small atomic Bose-Einstein condensate as an interferometric scanning probe to map out a microwave field near a chip surface with a few micrometers resolution. Using entanglement between the atoms we overcome the standard quantum…

Quantum Physics · Physics 2013-10-30 Caspar F. Ockeloen , Roman Schmied , Max F. Riedel , Philipp Treutlein

We consider quantum enhancement of direct-detection interferometric measurements to increase telescope resolution. We propose a protocol of measuring interferometric visibility function using imperfectly entangled states shared between…

Quantum Physics · Physics 2018-09-13 Siddhartha Santra , Brian T. Kirby , Vladimir S. Malinovsky , Michael Brodsky

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

Entanglement constitutes a key characteristic feature of quantum matter. Its detection, however, still faces major challenges. In this letter, we formulate a framework for probing entanglement based on machine learning techniques. The…

Quantum Physics · Physics 2021-08-18 Jun Yong Khoo , Markus Heyl

Correlation relations for the spin measurements on a pair of entangled particles scattered by the two separate arms of interferometers in hybrid setups of different types are investigated. Concurrence, entanglement of formation, quantum…

Quantum Physics · Physics 2023-09-06 M. E. Tunalioglu , H. O. Cildiroglu , A. U. Yilmazer

We develop an original approach for the quantitative characterisation of the entanglement properties of, possibly mixed, bi- and multipartite quantum states of arbitrary finite dimension. Particular emphasis is given to the derivation of…

Quantum Physics · Physics 2009-11-11 Florian Mintert , Andre R. R. Carvalho , Marek Kus , Andreas Buchleitner

This thesis focuses on the experimental creation and detection of a variety of quantum correlations using nuclear magnetic resonance hardware. Quantum entanglement, being most common and counter-intuitive, is one of the main type considered…

Quantum Physics · Physics 2019-05-16 Amandeep Singh

Entanglement is one of the fundamental properties of a quantum state and is a crucial differentiator between classical and quantum computation. There are many ways to define entanglement and its measure, depending on the problem or…

Quantum Physics · Physics 2025-01-07 Andrii Semenov , Niall Murphy , Simone Patscheider , Alessandra Bernardi , Elena Blokhina

Quantum entanglement offers powerful opportunities for enhancing measurement sensitivity beyond classical limits, with optical atomic clocks serving as a leading platform for such advances. This chapter introduces the principles of…

Quantum Physics · Physics 2025-12-04 Raphael Kaubruegger , Adam M. Kaufman

Although the realization of useful quantum computers poses significant challenges, swift progress in emerging quantum technologies is making this goal realistically approachable. In this context, one of the essential resources is quantum…

Quantum Physics · Physics 2022-01-11 Valeria Saggio , Philip Walther

We investigate the phase enhancement of quantum states subject to non-linear phase shifts. The optimal phase estimation of even entangled coherent states (ECSs) is shown to be better than that of NOON states and of odd ECS states with the…

Quantum Physics · Physics 2012-10-25 Jaewoo Joo , Kimin Park , Hyunseok Jeong , William J. Munro , Kae Nemoto , Timothy P. Spiller

Quantum entanglement is a fundamental resource for quantum information processing and is widely used in quantum communication, quantum computation and quantum metrology. Early research on quantum entanglement mainly focus on qubit states,…

Quantum Physics · Physics 2022-12-02 Linxiang Zhou , Qiao Xu , Tianfeng Feng , Xiaoqi Zhou

A method is introduced whereby two non-interacting quantum subsystems, that each interact with a third subsystem, are entangled via repeated projective measurements of the state of the third subsystem. A variety of physical examples are…

Quantum Physics · Physics 2007-05-23 Lian-Ao Wu , Daniel A. Lidar , Sara Schneider

The quantification of the entanglement present in a physical system is of para\-mount importance for fundamental research and many cutting-edge applications. Currently, achieving this goal requires either a priori knowledge on the system or…

Entanglement is a striking feature of quantum mechanics, and it has a key property called unextendibility. In this paper, we present a framework for quantifying and investigating the unextendibility of general bipartite quantum states.…

Quantum Physics · Physics 2024-03-28 Kun Wang , Xin Wang , Mark M. Wilde

An entangled quantum state of two or more particles or objects exhibits some of the most peculiar features of quantum mechanics. Entangled systems cannot be described independently of each other even though they may have an arbitrarily…

Mesoscale and Nanoscale Physics · Physics 2018-04-27 C. F. Ockeloen-Korppi , E. Damskagg , J. -M. Pirkkalainen , A. A. Clerk , F. Massel , M. J. Woolley , M. A. Sillanpaa

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