What is achieved by India now in quantum communications? and why is it so significant? (Image AI generated author’s copyright) A few days ago there was news about a breakthrough in communication technology by India’s Quantum communication mission. As usual there was media hype and in the flashy videos produced by media, what is achieved and why it is significant, was not understood and lost. Besides this media aggression, with the subject itself being so complex, it is almost impossible for a common man to understand what the hype is all about. Here is an attempt by me to make things slightly clearer. I hope my readers would appreciate it. Basically this news pertains to communication links. So obviously it should be our first task to understand these strange words that are not very familiar to most of us. Most of us now have a broadband connection in our homes. This broadband signal comes to us riding on a cable which surprisingly has no metal wire inside. This cable is connected to a router fixed in our house. So in simple terms this physical arrangement that effects transfer of broadband signal from broadband provider’s office to our home is a communication link. The broadband links that bring and carry away broadband signals do not carry now the signal on a wire, but rather as a pulsating laser beam (1310-1490 nm wavelength, upstream-downstream, Infrared region) that is sent through a tube inside the cable and that is why the link is also called an optical link. To send the data (in digital format) the laser beam is rapidly switched between two states (on-off). This is called modulation and in broadband transfers, intensity modulation is the usual method. Actually, signal processing is much more complex in reality, but to make things simple, I have described it in this simple fashion. Now let us come to the word “Quantum” used in news item. This term has come from a branch of Physics known as Quantum mechanics. The basic principle in this branch of physics is the “Heisenberg Uncertainty principle”. To understand this principle, let us now imagine an event. Suppose I am standing on the balcony of my house. There is a very large crowd of people standing in front of my house and a dear friend of mine “Divakar” is part of that crowd. I have a telescope with me, and I want to firstly locate “Diwakar” in the crowd and secondly want to find, the colour of the shirt, he is wearing. But the uncertainty principle tells us that I can find out only one of the two things I want to know. Divakar’s location or colour of his shirt, but never both the things. This is the basic postulate of all things Quantum. However, uncertainty principle does not apply to humans and applies rather to basic nuclear particles like electrons or photons. (Image AI generated author’s copyright) The communication link, about which we are hearing about here, exactly behaves in this fashion and is therefore called as Quantum communication. Before we find out little more about Quantum communication links, let us return to our broadband cable for a moment. Suppose I cut off my cable before it reaches my router and terminate both cut ends in a T joint, like plumbers do in our house. To the third end, suppose I connect another router. What would happen? All the broadband data flowing through that cable would be accessible to me. I would be eavesdropping. This is just not allowed in secured data links, where sanctity of data is paramount. (Image AI generated author’s copyright) Quantum communication links come into picture here. If someone tries eavesdropping in a Quantum link, the original data would be all distorted, because of Quantum principle, errors would prop up and the legal recipient would instantly find this out, because of the Quantum nature of the communication. To keep this discussion in grasp of common non-technical readers, we might add a few more details. In Quantum communication links, the data does not modulate a light beam but rather a single stream of the fundamental parti...
View On WordPress









