Telecommunication networks are certainly one of the cornerstones of the modern information society and one of the main drivers of the economy and provide a basis on which many daily activities can rely. Also, new technologies such as the Internet of Things, artificial intelligence, self-driving cars, 5G, etc. will not reach their full potential unless an infrastructure communication network meets their needs. Security is critical to their infrastructure and services. On the other hand, the development of Quantum computing technology in recent years and the construction of Quantum computers with very high processing power and solving very complex problems faster than current computers has made cybersecurity, computer security and communication devices a vital and important issue for governments. However, with the advancement of Quantum technology, these threats can be prevented by using Quantum methods to distribute keys, so Quantum cryptography is considered as an alternative to classical methods against Quantum computers and cyberattacks. Quantum key distribution is the most popular sub-branch of Quantum cryptography, and commercial examples are now available in the market. However, the implementation of Quantum key distribution networks in fiber optics, which is discussed in this paper, is one of the solutions that provide unconditional security through Quantum cryptography to establish secure communication. The distinguishing point of this article is to provide an overview of the latest research in the field of implementation of Quantum key distribution networks in fiber optics. In addition, the Quantum key distribution networks implemented in the world are reviewed and compared and the approach of different countries in this field is studied.

Currently, carbon Quantum dots have attracted considerable attention due to their unique properties and desirable advantages. High crystallinity, water solubility, good dispersibility, small size, low toxicity, inexpensive raw materials, high chemical stability, environmental compatibility, low cost, stability under light, desirable charge transfer with advanced electronic conductivity, as well as specific thermal and mechanical properties are some of these features. Carbon Quantum dots have various applications in different fields. Fabrication of precise chemical and biological sensors, bioimaging, solar cells, drug tracking, nanomedicine, light-emitting diodes (LEDs), and electrocatalysts are some of these applications. Biological sensors based on carbon Quantum dots are capable of detecting various metal ions, acids, proteins, biotin, polypeptides, DNA and miRNA, water pollutants, hematin, drugs, vitamins, and other chemicals. In the present study, the properties of carbon Quantum dots and some of their fabrication and applications methods have been addressed. In continuation of the paper, the effect of carbon Quantum dots on important factors in plants such as growth and development, photosynthesis, absorption and transportation of substances, resistance to biotic and abiotic stresses, as well as their application in agriculture has been investigated.

This study proposes a structure for graphene spaser (surface plasmon amplification by stimulated emission of radiation) and develops an electrostatic model for quantizing plasmonic modes. Using this model, one can analyze any spaser consisting of graphene in the electrostatic regime. The proposed structure is investigated analytically and the spasing condition is derived. We show that spasing can occur at some frequencies where the quality factor of plasmonic modes is higher than some particular minimum values. Finally, an algorithmic design procedure is proposed by which one can design a viable structure at a given frequency. As an example, a spaser with plasmon energy of 0. 1 eV is designed.

In this article, the interaction of an arbitrary number of Quantum dots behaving as artificial molecules with different energy levels and a multi-mode electromagnetic field is studied. We make the assumption that each Quantum dot can be represented as an atom with zero kinetic energy, and that all excitonic effects except dipole-dipole interactions may be disregarded. We use the Jaynes-Cummings-Paul model with applications to Quantum systems based on a time-dependent Hamiltonian and entangled states. We obtain a system of equations describing the interaction, and present a method to solve the equations analytically for a single mode field within the Rotating-Wave Approximation. As an example of the applicability of this approach, we solve the system of two, two-level Quantum dots in a lossless cavity with two modes of electromagnetic field. We, furthermore, study the evolution of entanglement by defining and computing the concurrency.