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Attempts at cloning a quantum system result in the introduction of imperfections in the state of the copies. This is a consequence of the no-cloning theorem, which is a fundamental law of quantum physics and the backbone of security for…

Quantum Physics · Physics 2016-08-17 Frédéric Bouchard , Robert Fickler , Robert W Boyd , Ebrahim Karimi

Basing on states and channels isomorphism we point out that semidefinite programming can be used as a quick test for nonzero one-way quantum channel capacity. This can be achieved by search of symmetric extensions of states isomorphic to a…

Quantum Physics · Physics 2015-06-26 Pawel Horodecki , Marcin L. Nowakowski

We study the quantumness of bipartite correlations by proposing a quantity that combines a measure of total correlations -- mutual information -- with the notion of broadcast copies -- i.e., generally nonfactorized copies -- of bipartite…

Quantum Physics · Physics 2009-07-17 M. Piani , M. Christandl , C. E. Mora , P. Horodecki

We investigate the role of symmetric quantum cloning machines (QCMs) in quantifying the mutual incompatibility of quantum observables. Specifically, we identify a cloning-based incompatibility measure whereby the incompatibility of a set of…

Quantum Physics · Physics 2021-09-20 Arindam Mitra , Prabha Mandayam

Entangled states that cannot be distilled to maximal entanglement are called bound entangled and they are often viewed as too weak to break the limitations of classical models. Here, we show a strongly contrasting result: that bound…

Quantum Physics · Physics 2026-03-09 Armin Tavakoli , Carles Roch i Carceller , Lucas Tendick , Tamás Vértesi

We study the separability of permutationally symmetric quantum states. We show that for bipartite symmetric systems most of the relevant entanglement criteria coincide. However, we provide a method to generate examples of bound entangled…

Quantum Physics · Physics 2009-05-12 Geza Toth , Otfried Gühne

No-cloning theorem forbids perfect cloning of an unknown quantum state. A universal quantum cloning machine (UQCM), capable of producing two copies of any input qubit with the optimal fidelity, is of fundamental interest and has…

It is well known that it is impossible to clone an arbitrary quantum state. However, this inability does not lead directly to no-cloning of quantum coherence. Here, we show that it is impossible to clone the coherence of an arbitrary…

Cloning machines, that is, transformations that achieve the best approximate copying of a quantum state compatible with the no-cloning theorem, have been a fundamental research topic over the last five years. This study is of particular…

Quantum Physics · Physics 2007-05-23 Nicolas J. Cerf

In the companion to this paper, we described a generalization of the deterministic quantum cloning process, called enscription, which utilizes entanglement in order to achieve the "copying" of (certain) sets of distinct quantum states which…

Quantum Physics · Physics 2007-05-23 Randall Espinoza , Tom Imbo , Paul Lopata

We investigate the dense coding in the case of non-symmetric Hilbert spaces of the sender and receiver's particles sharing the quantum maximally entangled state. The efficiency of classical information gain is also considered. We conclude…

Quantum Physics · Physics 2009-11-10 Fengli Yan , Meiyu Wang

We present Quantum Cloning Machines (QCM) that transform N identical qubits into $M>N$ identical copies and we prove that the fidelity (quality) of these copies is optimal. The connection between cloning and measurement is discussed in…

Quantum Physics · Physics 2009-01-23 N. Gisin , S. Massar

We establish a quantitative connection between the amount of lost classical information about a quantum state and the concomitant loss of entanglement. Using methods that have been developed for the optimal purification of mixed states we…

Quantum Physics · Physics 2013-09-03 J. Eisert , T. Felbinger , P. Papadopoulos , M. B. Plenio , M. Wilkens

A qubit (a spin-1/2 particle) prepared in the up state is scattered by local spin-flipping potentials produced by the two target qubits (two fixed spins), both prepared in the down state, to generate an entangled state in the latter when…

Quantum Physics · Physics 2009-07-11 Yuichiro Hida , Hiromichi Nakazato , Kazuya Yuasa , Yasser Omar

High-dimensional entanglement is a valuable resource for quantum communication, and photon pairs entangled in orbital angular momentum are commonly used for encoding high-dimensional quantum states. However, methods for preparation of…

Quantum Physics · Physics 2018-12-19 Egor Kovlakov , Stanislav Straupe , Sergey Kulik

Copying information is an elementary operation in classical information processing. However, copying seems rather different in the quantum regime. Since the discovery of the universal quantum cloning machine, much has been found from the…

Quantum Physics · Physics 2007-05-23 K. Maruyama , P. L. Knight

The impossibility to clone an unknown quantum state is a powerful principle to understand the nature of quantum mechanics, especially within the context of quantum computing and quantum information. This principle has been generalized to…

Quantum Physics · Physics 2009-11-11 Erik Sjöqvist , Johan Åberg

Unextendibility of quantum states and channels is inextricably linked to the no-cloning theorem of quantum mechanics, it has played an important role in understanding and quantifying entanglement, and more recently it has found applications…

Quantum Physics · Physics 2025-12-01 Vishal Singh , Theshani Nuradha , Mark M. Wilde

Quantum state sharing is a protocol where perfect reconstruction of quantum states is achieved with incomplete or partial information in a multi-partite quantum networks. Quantum state sharing allows for secure communication in a quantum…

We investigate the probabilistic cloning and purification of quantum states. The performance of these probabilistic operations is quantified by the average fidelity between the ideal and actual output states. We provide a simple formula for…

Quantum Physics · Physics 2009-11-10 Jaromir Fiurasek
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