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We show the possibility to improve the measurement sensitivity of a weak force by using two meters in an entangled state. This latter can be achieved by exploiting radiation pressure effects.

Quantum Physics · Physics 2009-11-07 Stefano Mancini , Paolo Tombesi

We find that the asymptotic entanglement of assistance of a general bipartite mixed state is equal to the smaller of its two local entropies. Our protocol gives rise to the asymptotically optimal EPR pair distillation procedure for a given…

Quantum Physics · Physics 2007-05-23 John A. Smolin , Frank Verstraete , Andreas Winter

We show that the maximum entanglement in a composite system corresponds to the maximum uncertainty and maximum correlation of local measurements.

Quantum Physics · Physics 2007-05-23 Alexander A. Klyachko , Alexander S. Shumovsky

A recently proposed purification method, in which the Zeno-like measurements of a subsystem can bring about a distillation of another subsystem in interaction with the former, is utilized to yield entangled states between distant systems.…

Quantum Physics · Physics 2007-05-23 G. Compagno , A. Messina , H. Nakazato , A. Napoli , M. Unoki , K. Yuasa

Adding the maximally mixed state with some weight to the entanglement system leads to disentanglement of the latter. For each predefined entangled state there exists a minimal value of this weight for which the system loses its entanglement…

Quantum Physics · Physics 2021-09-01 Yu. S. Krynytskyi , A. R. Kuzmak

We present a measure of entanglement that can be computed effectively for any mixed state of an arbitrary bipartite system. We show that it does not increase under local manipulations of the system, and use it to obtain a bound on the…

Quantum Physics · Physics 2009-11-07 G. Vidal , R. F. Werner

It has been shown that entanglement distillation of Gaussian entangled states by means of local photon subtraction can be improved by local Gaussian transformations. Here we show that a similar effect can be expected for the distillation of…

Quantum Physics · Physics 2013-04-24 Anders Tipsmark , Jonas S. Neergaard-Nielsen , Ulrik L. Andersen

We find a minimal set of necessary and sufficient conditions for the existence of a local procedure that converts a finite pure state into one of a set of possible final states. This result provides a powerful method for obtaining optimal…

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

To quantify the entanglement is one of the most important topics in quantum entanglement theory. In [arXiv: 2006.12408], the authors proposed a method to build a measure from the orginal domain to a larger one. Here we apply that method to…

Quantum Physics · Physics 2021-04-21 Xian Shi , Lin Chen

We introduce a simple, experimentally realisable, entanglement manipulation protocol for exploring mixed state entanglement. We show that for both non-maximally entangled pure, and mixed polarisation-entangled two qubit states, an increase…

Quantum Physics · Physics 2009-11-06 R. T. Thew , W. J. Munro

An entangled quantum state is considered by applying a local photon excitation to each mode of an entangled coherent state. The entanglement property is investigated in terms of the entropy of entanglement. It is shown that applying a…

Quantum Physics · Physics 2023-04-13 Arpita Chatterjee

The problem of the experimental determination of the amount of entanglement of a bipartite pure state is addressed. We show that measuring a single observable does not suffice to determine the entanglement of a given unknown pure state of…

Quantum Physics · Physics 2009-10-31 J. M. G. Sancho , S. F. Huelga

Entangled coherent states are shown to emerge, with high fidelity, when mixing coherent and squeezed vacuum states of light on a beam-splitter. These maximally entangled states, where photons bunch at the exit of a beamsplitter, are…

Quantum Physics · Physics 2019-05-31 Yonatan Israel , Lior Cohen , Xin-Bing Song , Jaewoo Joo , Hagai S. Eisenberg , Yaron Silberberg

We consider mixed states of two qubits and show under which global unitary operations their entanglement is maximized. This leads to a class of states that is a generalization of the Bell states. Three measures of entanglement are…

Quantum Physics · Physics 2009-11-06 Frank Verstraete , Koenraad Audenaert , Tijl De Bie , Bart De Moor

The idea of exploiting maximally-entangled states as a resource lies at the core of several modalities of quantum information processing, including secure quantum communication, quantum computation, and quantum sensing. However, due to…

Quantum Physics · Physics 2023-05-31 Andrea Rodriguez-Blanco , K. Birgitta Whaley , Alejandro Bermudez

We introduce local filters as a means to detect the entanglement of bound entangled states which do not yield to detection by witnesses based on positive (P) maps which are not completely positive (CP). We demonstrate how such…

Quantum Physics · Physics 2017-09-13 Debmalya Das , Ritabrata Sengupta , Arvind

We consider the actions of protocols involving local quantum operations and classical communication (LQCC) on a single system consisting of two separated qubits. We give a complete description of the orbits of the space of states under LQCC…

Quantum Physics · Physics 2009-10-31 Adrian Kent , Noah Linden , Serge Massar

We present two results which combined enable one to reliably detect multimode, multipartite entanglement in the presence of measurement errors. The first result leads to a method to compute the best (approximated) physical covariance matrix…

Quantum Physics · Physics 2016-10-05 E. Shchukin , P. van Loock

We analyze tight informationally complete measurements for arbitrarily large multipartite systems and study their configurations of entanglement. We demonstrate that tight measurements cannot be exclusively composed neither of fully…

Quantum Physics · Physics 2018-06-26 Jakub Czartowski , Dardo Goyeneche , Karol Życzkowski

We present a general theoretical method to generate maximally entangled mixed states of a pair of photons initially prepared in the singlet polarization state. This method requires only local operations upon a single photon of the pair and…

Quantum Physics · Physics 2009-11-13 A. Aiello , G. Puentes , D. Voigt , J. P. Woerdman