Hello. We start our module dedicated to one of the most famous and most known applications of quantum technologies, quantum informatics, which is called quantum key distribution. In our module, we will cover some basic definitions and some basic protocols, simple attacks, and the questions concerning the security of quantum key distribution protocols. Also, we will cover some questions regarding the current situation in this domain. Quantum technologies do use separate individual quantum objects like individual molecules, atoms, electrons, photons, and also due this, some interesting and important quantum effects like superposition of quantum states, entanglement, no-cloning theorem, uncertainty principle, and tunnel effect. We also can mention some other effects used in quantum technologies, for example, quantum teleportation, which allows to transmit a quantum state and photo parties, usually have some parts of intelligent quantum state. Quantum mechanics appeared in the beginning of 20th century in 1900, Max Planck assumed that energy is radiated by portions from the objects. By using this assumption, he described thermal spectrum of a radiation of blood-body. In 1905, Albert Einstein postulated that light consists of portions so-called photons, and by using this assumption here, described later called photoelectric effect. For this description, he was awarded by Nobel Prize. There were some another brilliant physicist who had great impact in quantum mechanics, for example, Niels Bohr, Heisenberg, Schrodinger, Pauli, and Dirac, but we will not go in details. So the first three or four decades of the 20th century, some basic laws and basic principles of quantum mechanics was studied and stated. But then, some applications begin to appear. In 1938, nuclear magnetic resonance was discovered, and now it's widely used in tomography. In 1954, in the book of [inaudible] , a Maser was described and now was a technologist who have a great applications in many domains. To filter some applications issues to no effect also were introduced. But all these applications due to these sets of particles beams. But in 2012, a Nobel Prize in physics, it was given to two physicists, David J. Wineland and Serge Haroche for groundbreaking experimental methods that enable measuring and manipulation of individual quantum systems. Their results can be used in such applications of quantum technologies like a quantum algorithm for quantum computation, quantum cryptography including quantum key distribution, quantum information, and quantum control. Quantum computation is potentially a domain which will have impact on a classical cryptography. For example, today we know two algorithms; Shor's algorithm and Grover's algorithm. Shor's algorithm will allow us to factorize integers in a polynomial time by using quantum computers. Is this with the probabilistic algorithm. We know that, for example, Adi Shamir-Adelman cryptosystem, the security of this cryptosystem is based on the fact that as this problem is hard to solve on a classical computer. So we don't know polynomial algorithms which solves this problem. Another algorithm is Grover algorithm introduced by Lov Grover. It allows to solve a Boolean equation, fx is equal to 1 where fx is a sum Boolean function if is rate 1. The American organization, the National Institute of Standards and Technology recently has published a report on post quantum cryptography in each amongst other things a possible influence of appearance of scalable quantum computers and classical cryptography has been closed. They mentioned the Grover's algorithm, Shor's algorithm, and they also mentioned that some crypto systems, for example, as I mentioned RSA, Elliptic Curve Cryptography and Finite Field Cryptography will all be secure. The symmetric key cryptography protocols, for example, Advanced Encryption Standard, will demand more longer key size. But at the same time, there are rather tricks for a big demands for a quantum computer in order to implement, for example, Shor's algorithm. In order to implement Shor's algorithm on real size key lens of RSA, you'll demand for quantum computer to operate these millions of qubit. Now as this bound is not reachable still. The question, is it a cause of concern? Is it discussed? Often such diagram is shown, and in this diagram, three notions are used X, Y, Z. X is at time needed to keep the cryptographic keys in secret, Y is time needed to implement post-quantum cryptography which will be secure to attacks which use a quantum computer. That is time before quantum computer comes. If that is smaller than x plus y, then some cause of concern appears. We can estimate x and y somehow, but what about that? This question I will refer to the works of Michele Mosca. One of the most famous and known specialist is the domain of quantum computation, and he also studies the possible potential influence of quantum computation on classical cryptography. In his reports, it's mentioned that we can expect the appearance over high-scale quantum computer on which we will be able to implement quantum algorithms which will have impact on classical cryptography in maybe decades of years. But nevertheless, as a goal of invention can develop in some ways of data security which are secure against attacks issues, quantum computers is a goal worth boasting.
