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We present an alternative approach to unveil a different kind of entanglement in bipartite quantum states whose diagonal zero patterns in suitable matrix representations admit a nice description in terms of triangle-free graphs. Upon…

Quantum Physics · Physics 2021-03-30 Satvik Singh

We investigate the usefulness of side entanglement in discriminating between two generic qubit channels, {\ up to unitary pre- and post-processing,} and determine exact conditions under which it does enhance (as well as conditions under…

Quantum Physics · Physics 2023-10-25 Samad Khabbazi Oskouei , Stefano Mancini , Milajiguli Rexiti

Quantum hypothesis testing has been greatly advanced for the binary discrimination of two states, or two channels. In this setting, we already know that quantum entanglement can be used to enhance the discrimination of two bosonic channels.…

Quantum Physics · Physics 2020-07-30 Quntao Zhuang , Stefano Pirandola

The problem of bound entanglement detection is a challenging aspect of quantum information theory for higher dimensional systems. Here, we propose an indecomposable positive map for two-qutrit systems, which is shown to generate a class of…

We introduce two methods for quantum process and detector tomography. In the quantum process tomography method, we develop an analytical procedure for projecting the linear inversion estimation of a quantum channel onto the set of…

Quantum Physics · Physics 2025-01-10 Júlia Barberà-Rodríguez , Leonardo Zambrano , Antonio Acín , Donato Farina

We introduce an experimental procedure for the detection of quantum entanglement of an unknown quantum state with as few measurements as possible. The method requires neither a priori knowledge of the state nor a shared reference frame…

In quantum information theory, the reliable and effective detection of entanglement is of paramount importance. However, given an unknown state, assessing its entanglement is a challenging task. To attack this problem, we investigate the…

Quantum Physics · Physics 2015-12-09 Jochen Szangolies , Hermann Kampermann , Dagmar Bruß

Measurements in the quantum domain can exceed classical notions. This concerns fundamental questions about the nature of the measurement process itself, as well as applications, such as their function as building blocks of quantum…

Quantum Physics · Physics 2023-02-02 Jan Sperling , Ilaria Gianani , Marco Barbieri , Elizabeth Agudelo

In this paper, we discuss some general connections between the notions of positive map, weak majorization and entropic inequalities in the context of detection of entanglement among bipartite quantum systems. First, basing on the fact that…

Quantum Physics · Physics 2009-07-09 Remigiusz Augusiak , Julia Stasińska

We study the entanglement detection by using mutually unbiased measurements and provide a quantum separability criterion that can be experimentally implemented for arbitrary $d$-dimensional bipartite systems. We show that this criterion is…

Quantum Physics · Physics 2015-06-22 Bin Chen , Teng Ma , Shao-Ming Fei

The set of doubly-stochastic quantum channels and its subset of mixtures of unitaries are investigated. We provide a detailed analysis of their structure together with computable criteria for the separation of the two sets. When applied to…

Quantum Physics · Physics 2014-07-30 Christian B. Mendl , Michael M. Wolf

Originated from the superposition principle in quantum mechanics, coherence has been extensively studied as a kind important resource in quantum information processing. We investigate the distinguishability of coherence-breaking channels…

Quantum Physics · Physics 2019-09-04 Long-Mei Yang , Tao Li , Shao-Ming Fei , Zhi-Xi Wang

In this study, we introduce an autonomous method for addressing the detection and classification of quantum entanglement, a core element of quantum mechanics that has yet to be fully understood. We employ a multi-layer perceptron to…

Quantum Physics · Physics 2024-10-21 Julio Ureña , Antonio Sojo , Juani Bermejo , Daniel Manzano

There are processes that cannot generate entanglement but may, nevertheless, amplify entanglement already present in a system. Here, we show that a non-entangling operation can increase the Schmidt number of a quantum state only if it can…

Quantum Physics · Physics 2026-05-07 Julien Pinske , Jan Sperling , Klaus Mølmer

Quantum entanglement, a fundamental property ensuring security of key distribution and efficiency of quantum computing, is extremely sensitive to decoherence. Different procedures have been developed in order to recover entanglement after…

Quantum Physics · Physics 2008-04-23 Fabio Sciarrino , Eleonora Nagali , Francesco De Martini , Miroslav Gavenda , Radim Filip

This work is the development and analysis of the recently proposed quantum cryptographic protocol, based on the use of the two-mode coherently correlated states. The protocol is supplied with the cyrptographic control procedures. The…

Quantum Physics · Physics 2015-06-26 Constantin V. Usenko , Vladyslav C. Usenko

Ensuring the non-entanglement-breaking (non-EB) property of quantum channels is crucial for the effective distribution and storage of quantum states. However, a practical method for direct and accurate certification of the non-EB feature is…

In this paper we initiate the study of entanglement-breaking (EB) superchannels. These are processes that always yield separable maps when acting on one side of a bipartite completely positive (CP) map. EB superchannels are a generalization…

Quantum Physics · Physics 2020-07-21 Senrui Chen , Eric Chitambar

In quantum communication protocols, the use of photon-number-resolving detectors could open new perspectives by broadening the way to encode and decode information, and merging the properties of discrete and continuous variables. In this…

We construct a family of positive but not completely positive linear maps acting on four dimensional space. We employ these maps to detect bound entanglement in high dimensional quantum systems.

Quantum Physics · Physics 2026-04-21 Mazhar Ali