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The certification of entanglement in multipartite scenarios is crucial for the advancement of quantum technologies, particularly for the realization of large-scale quantum networks. Here, we introduce a method to certify the structure of…

Quantum Physics · Physics 2026-04-07 Carles Roch I Carceller

Usually, the three-tangle of a tripartite pure state of qubits can be directly measured with the simultaneous preparation of a not-less-than-four-fold copy of the state. We show that the exact genuine tripartite entanglement for…

Quantum Physics · Physics 2016-04-20 Chang-shui Yu , Bao-qing Guo , Si-ren Yang

We study the problem of universal quantum cloning -- taking several identical copies of a pure but unknown quantum state and producing further copies. While it is well known that it is impossible to perfectly reproduce the state, how well…

Quantum Physics · Physics 2016-08-09 Alastair Kay

While it has recently been demonstrated how to certify the maximal amount of randomness from any pure two-qubit entangled state in a device-independent way [E. Woodhead et al., Phys. Rev. Research 2, 042028(R)(2020)], the problem of optimal…

We introduce a new entanglement measure based on optimal entanglement witness. First of all, we show that the entanglement measure satisfies some necessary properties, including zero entanglements for all separable states, convexity,…

Quantum Physics · Physics 2024-02-20 Nan Yang , Jiaji Wu , Xianyun Dong , Longyu Xiao , Jing Wang , Ming Li

Quantum state tomography is the problem of estimating a given quantum state. Usually, it is required to run the quantum experiment - state preparation, state evolution, measurement - several times to be able to estimate the output quantum…

General Physics · Physics 2025-04-30 Shibdas Roy , Filippo Caruso , Srushti Patil , Anumita Mukhopadhyay

Detection of entanglement in quantum networks consisting of many parties is one of the important steps towards building quantum communication and computation networks. We consider a scenario where the measurement devices used for this…

Quantum Physics · Physics 2017-05-03 Ivan Šupić , Paul Skrzypczyk , Daniel Cavalcanti

Entanglement distillation, an essential quantum information processing task, refers to the conversion from multiple copies of noisy entangled states to a smaller number of highly entangled states. In this work, we study the non-asymptotic…

Quantum Physics · Physics 2019-10-03 Kun Fang , Xin Wang , Marco Tomamichel , Runyao Duan

Recent work has shown that use of quantum feedback can significantly enhance both the speed and success rate of measurement-based remote entanglement generation, but it is generally unknown what feedback protocols are optimal for these…

Quantum Physics · Physics 2017-07-17 Leigh S. Martin , Mahrud Sayrafi , K. Birgitta Whaley

It is a specific type of quantum correlated state that achieves optimal precision in parameterestimation under unitary encoding. We consider the potential experimental limitation on probe entanglement, and find a relation between achievable…

Quantum Physics · Physics 2026-01-06 Debarupa Saha , Ujjwal Sen

The study of properties of randomly chosen quantum states has in recent years led to many insights into quantum entanglement. In this work, we study private quantum states from this point of view. Private quantum states are bipartite…

Quantum Physics · Physics 2024-09-02 Matthias Christandl , Roberto Ferrara , Cécilia Lancien

Quantum state tomography is an integral part of quantum computation and offers the starting point for the validation of various quantum devices. One of the central tasks in the field of state tomography is to reconstruct with high fidelity,…

Quantum Physics · Physics 2022-12-21 Rishabh Gupta , Manas Sajjan , Raphael D. Levine , Sabre Kais

The impossibility of deterministic and error-free discrimination among nonorthogonal quantum states lies at the core of quantum theory and constitutes a primitive for secure quantum communication. Demanding determinism leads to errors,…

Quantum Physics · Physics 2021-12-21 M. A. Solís-Prosser , O. Jiménez , A. Delgado , L. Neves

The most simplest form of quantum network is an one dimensional quantum network with a single player in each node. In remote entanglement distribution each of the players carry out measurement at the intermediate nodes to produce an…

Quantum Physics · Physics 2023-06-27 Ganesh Mylavarapu , Indranil Chakrabarty , Kaushiki Mukherjee , Minyi Huang , Junde Wu

We investigate optimal discrimination between two projective single-qubit measurements in a scenario where the measurement can be performed only once. We consider general setting involving a tunable fraction of inconclusive outcomes and we…

Quantum Physics · Physics 2014-12-01 M. Mikova , M. Sedlak , I. Straka , M. Micuda , M. Ziman , M. Jezek , M. Dusek , J. Fiurasek

Suppose we have an unknown multipartite quantum state, how can we experimentally find out whether it is genuine multipartite entangled or not? Recall that even for a bipartite quantum state whose density matrix is known, it is already…

Quantum Physics · Physics 2022-11-16 Zhenyu Chen , Xiaodie Lin , Zhaohui Wei

The quantum analogue of the equality function, known as the quantum state identity problem, is the task of deciding whether $n$ unknown quantum states are equal or unequal, given the promise that all states are either pairwise orthogonal or…

Quantum Physics · Physics 2026-04-15 Harry Buhrman , Dmitry Grinko , Philip Verduyn Lunel , Jordi Weggemans

Quantifying entanglement is a work in progress which is important for the active field of quantum information and computation. A measure of bipartite pure state entanglement is proposed here, named entanglement coherence, which is…

Quantum Physics · Physics 2022-02-15 Neha Pathania , Tabish Qureshi

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

We describe an optimized, self-correcting procedure for the Bayesian inference of pure quantum states. By analyzing the history of measurement outcomes at each step, the procedure returns the most likely pure state, as well as the optimal…

Quantum Physics · Physics 2015-09-14 Amir Kalev , Itay Hen