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We show that any two different unitary operations acting on an arbitrary multipartite quantum system can be perfectly distinguishable by local operations and classical communication when a finite number of runs is allowed. We then directly…

Quantum Physics · Physics 2011-11-09 Runyao Duan , Yuan Feng , Mingsheng Ying

We study two complementary diagnostics of bipartite quantum channels, namely fidelity preservation across different classes of input states and entanglement generation from product inputs, given by properly defined entangling power for…

Quantum Physics · Physics 2026-05-27 Marcin Rudziński , Gianluigi Tartaglione , Karol Życzkowski

We exhibit an orthogonal set of product states of two three-state particles that nevertheless cannot be reliably distinguished by a pair of separated observers ignorant of which of the states has been presented to them, even if the…

We address the problem of the robustness of entanglement of bipartite systems (qubits) interacting with dynamically independent environments. In particular, we focus on characterization of so-called local entanglement-annihilating two-qubit…

Quantum Physics · Physics 2012-01-05 Sergey N. Filippov , Tomas Rybar , Mario Ziman

We present numerical results on the capacities of two-qubit unitary operations for creating entanglement and increasing the Holevo information of an ensemble. In all cases tested, the maximum values calculated for the capacities based on…

Quantum Physics · Physics 2007-05-23 Dominic W. Berry , Barry C. Sanders

We study information transmission over a fully correlated amplitude damping channel acting on two qubits. We derive the single-shot classical channel capacity and show that entanglement is needed to achieve the channel best performance. We…

Quantum Physics · Physics 2013-11-01 A. D'Arrigo , G. Benenti , G. Falci , C. Macchiavello

Operator entanglement of two-qubit joint unitary operations is revisited. Schmidt number is an important attribute of a two-qubit unitary operation, and may have connection with the entanglement measure of the unitary operator. We found the…

Quantum Physics · Physics 2015-06-04 Hui-Zhi Xia , Chao Li , Qing Yang , Ming Yang , Zhuo-Liang Cao

The information obtained from the operation of a quantum gate on only two complementary sets of input states is sufficient to estimate the quantum process fidelity of the gate. In the case of entangling gates, these conditions can be used…

Quantum Physics · Physics 2017-08-23 Holger F. Hofmann , Ryo Okamoto , Shigeki Takeuchi

Entanglement serves as a fundamental resource for various quantum information processing tasks. Fidelity of entanglement (which measures the proximity to a maximally entangled state) and various quantum entropies are key indicators for…

Quantum Physics · Physics 2025-10-21 Komal Kumar , Bivas Mallick , Tapaswini Patro , Nirman Ganguly

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

While quantum circuits built from two-particle dual-unitary (maximally entangled) operators serve as minimal models of typically nonintegrable many-body systems, the construction and characterization of dual-unitary operators themselves are…

Quantum Physics · Physics 2023-01-20 Suhail Ahmad Rather , S. Aravinda , Arul Lakshminarayan

Bipartite operations underpin both classical communication and entanglement generation. Using a superposition of classical messages, we show that the capacity of a two-qubit operation for error-free entanglement-assisted bidirectional…

Quantum Physics · Physics 2007-05-23 Dominic W. Berry , Barry C. Sanders

The entanglement in operator space is a well established measure for the complexity of the quantum many-body dynamics. In particular, that of local operators has recently been proposed as dynamical chaos indicator, i.e. as a quantity able…

Statistical Mechanics · Physics 2020-04-29 Bruno Bertini , Pavel Kos , Tomaz Prosen

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

Motivated by recent discussions of entanglement in the context of high energy scattering, we consider the relation between the entanglement entropy of a highly excited state of a quantum system and the classical entanglement entropy of the…

Quantum Physics · Physics 2023-01-18 Haowu Duan , Alex Kovner , Vladimir V. Skokov

The ability to reach a maximally entangled state from a separable one through the use of a two-qubit unitary operator is analyzed for mixed states. This extension from the known case of pure states shows that there are at least two families…

Quantum Physics · Physics 2018-04-06 Zhe Guan , Huan He , Yong-Jian Han , Chuan-Feng Li , Fernando Galve , Guang-Can Guo

Entangling and disentangling capacities are the key manifestation of the nonlocal content of a quantum operation. A lot of effort has been put recently into investigating (dis)entangling capacities of unitary operations, but very little is…

Quantum Physics · Physics 2007-05-23 Berry Groisman

We quantify the capability of creating entanglement for a general physical interaction acting on two qubits. We give a procedure for optimizing the generation of entanglement. We also show that a Hamiltonian can create more entanglement if…

Quantum Physics · Physics 2011-06-02 W. Dür , G. Vidal , J. I. Cirac , N. Linden , S. Popescu

Entanglement is sometimes helpful in distinguishing between quantum operations, as differences between quantum operations can become magnified when their inputs are entangled with auxiliary systems. Bounds on the dimension of the auxiliary…

Quantum Physics · Physics 2008-04-18 John Watrous

We introduce a series of quantities which characterizes a given local operator in conformal field theories from the viewpoint of quantum entanglement. It is defined by the increased amount of (Renyi) entanglement entropy at late time for an…

High Energy Physics - Theory · Physics 2014-03-26 Masahiro Nozaki , Tokiro Numasawa , Tadashi Takayanagi