Hello, everyone. My name is Sergey Sysoev. I would like to welcome you to the course; Quantum Computing, Less Formulas - More Understanding. As in all my courses, I would first like to explain the course name, and what students can expect from it. As you already see, our main subject will be quantum computing, but what about this part? Less formulas than where? Well, honestly it is not my first course on the subject. Here on Coursera, you can find the course; The Introduction to Quantum Computing, which is mostly dedicated to quantum algorithms. If you haven't seen it yet, I encourage you to do so later. Now that introductory course is based on mathematical model of quantum computing, given very little explanation of where it comes from, this leads to lots of math but less understanding of physical nature of quantum computing and its power. It is really difficult to describe complicated quantum algorithms, not using complicated math, but maybe it is not necessary if you just want to understand how a quantum computer works. An idea came into my mind to make the second course more explanatory and less rigorous but not just that. This second course has a different focus. Instead of algorithms, we are going to concentrate more on the physical nature of a quantum computer. This will require less math and may serve as a good preparation for that and other introductory course. Let's take a look at the syllabus. The first week, which is this week, is dedicated to two important questions: why quantum computers are so powerful? Why it is so hard to implement them. Because as you probably know, there's no useful quantum computer implemented in the world up to this time. No math above the school level is required for understanding this week material. This week is enough for those of you who are just interested in basics of quantum computing and don't want to dig deeper into it. The second and the third weeks are about the mathematical model of quantum computing, and how it grows out from physics. The students who study the mathematical model in the introductory course often ask questions about the origins of mathematical model. Here, instead of introducing mathematical model as is, as we did in the introductory course, we're going to explain where it comes from. Some more prerequisites are required here. I assume that you understand what a differential equation is, and what is a solution of a differential equation, and what a complex number is and functions on complex numbers, etc. Also, we will use the notion of a vector space and buzzes of that space. The fourth week is all about the mathematical tools of quantum mechanics. As always, I don't expect from you any background in quantum mechanics, but its mathematical language is used everywhere in the field of quantum computing. This week is very much connected to the material of the second and the third weeks. Since the course name promises less formulas, I'll try to uncover only the tip of the iceberg here. Still, it will be very useful for you if you are going to continue learning and take the introductory course, for example. Under week 5, we will consider some basic algorithms concerning quantum teleportation and quantum cryptography. However, the course name says less formulas, it does not mean there will be no formulas at all. Still, the course material is more focused on understanding than on calculations and rigorous proofs. I hope you will enjoy it. Let's start learning.