Graph representation of quantum states is becoming an increasingly important area of research to investigate combinatorial properties of quantum states which are nontrivial to comprehend in standard linear algebraic density matrix based approach of quantum states. In this paper, we propose a general weighted directed graph framework for investigating properties of a large class of quantum states which are defined by three types of Laplacian matrices associated with such graphs. We generalize the standard framework of defining density matrices from simple connected graphs to density matrices using both combinatorial and signless Laplacian matrices associated with weighted directed graphs with complex edge weights and with/without loops. We also introduce a new notion of Laplacian matrix which we call signed Laplacian matrix associated with such graphs. We produce necessary and/or sufficient conditions for such graphs to represent pure and mixed quantum states. Using these criteria we finally determine the graphs whose corresponding density matrices represent entangled pure states which are well-known and important for quantum computation applications. It is important to observe that all these entangled pure states share a common combinatorial structure.

Internet of things (IoT) is made up of many devices like sensors, tags, actuators, mobile devices, and many more. These devices interact with each other without human interaction. Radio-frequency identification (RFID) devices are used to track people, assets, objects, etc. Along with the small memory capacity and low-power battery issues, these devices suffer from various security-related issues. These security threats include attacks such as replay, disclosure, tracking, offline guessing, denial of service attacks, and many more. In the last few decades, the researchers have suggested various security approaches to overcome these vulnerabilities. Hence, this paper discusses various possible attacks that can occur on an RFID system, and several security schemes that have been proposed to handle these attacks. First, the works presents the architecture of IoT in detail. Second, all possible attacks are described by categorizing them into confidentiality, integrity, and availability. Then, taxonomy of various security schemes, to deal with these attacks, is discussed under the criteria cryptography approaches, privacy, authentication, authorization, and availability. Finally, the paper describes various issues and challenges to have a better understanding of scope of the future research in the field of RFID security.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS -CoV-2), has become an unprecedented public health crisis. To tackle this crisis in an effecti ve way di fferent computational soluti ons invol vi ng artificial intelligence and machine learning have been propounded by researchers across the worl d. Artificial Intelligence has changed the landscape of the healthcare industry and is being used by many corporations and g overnments around the worl d to tackle health care issues and hence, it finds applications in these troubli ng times as well. The internet speciall y google scholar scoured for relevant and accurate applications of machine learning and deep learning in sol vi ng the issues of this pandemic. The di fferent applications include diagnosis, mortality rate pre dic tion, vaccine de velopment, dr ug de velopme nt, sentiment analysis regarding COVID-19 comments and misinformation detection. A systematic study presents the best working models in the respective field.

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We propose a generalized form of optimal teleportation witness to demonstrate their importance in experimental detection of the larger set of entangled states useful for teleportation in higher dimensional systems. The interesting properties of our witness reveal that teleportation witness can be used to characterize mixed state entanglement using Schmidt numbers. Our results show that while every teleportation witness is also a entanglement witness, the converse is not true. Also, we show that a hermitian operator is a teleportation witness iff it is a decomposable entanglement witness. In addition, we analyze the practical significance of our study by decomposing our teleportation witness in terms of Pauli and Gell-Mann matrices, which are experimentally measurable quantities.