Quantum theory is a very complex and weird theory. If a tiny object such as one single photon (particle) of light has a choice of passing through the left for right hole of a paper with two holes, then it will be passing through both the holes. An experiment has been conducted and it showed light passing through both holes when only one photon of light was produced. Another example is of a cat, put in a box, which was fed with poison. The poison may or may not kill the cat. The box is covered. Is the cat dead or alive? The answer, according to quantum theory is that the cat is both dead and alive.
Quantum theory can be summarized into the sentence: if we do not know about what state an object is in when it has more than one state to be in, then it is said to be in both the states.
Quantum theory may seem strange, but it is the only theory which can explain how DNA works, how the sun shines, how to design the laser that reads CDs and even allow scientists to calculate the consequences of nuclear reactions in power stations.
We do not know which hole the photon of light passes through, so it passes through both. We do not know whether the cat is dead or alive, so it is both dead and alive.
Computers nowadays calculate by using binary numbers formed by particles. For example, if a particle is to the east, then it represents ‘1'. If it is to the west, it represents ‘0'. So, seven particles in the order “west, west, west, east, west, east, east” would represent 0001011 or 11. If we want to change it, then we can fire a beam of energy to the particles. If it is a strong one, then it will change the position of the particle to one that you want to change it to. If it is a weak beam, then it may or may not change the position. If we block ourselves from the particles so that we do not know which state(position) it is in, then, by applying quantum theory, it is both in the west and in the east. By using just seven particles, it can represent 128 possibilities. Thus, it is able to make 128 calculations at one time, instead of only 1 calculation at a time. So, we can use them to break RSA and PGP, which relies on the fact that it will take 12 million times the age of the universe to check every single digit from 1 to 10 to the power of 308 to find out if it is a factor. If we use 10 particles, then the number of calculations we can make is 2 to the power of 10 , which is 1024. If we use 100 particles, then the number would be 2 ot the power of 100 , which is 1267650600228229401496703205376 or 10 to the power of 30 . If we use 1000 particles, then the answer is 1.07150860718626732094842504296E +301. 10 to the power of 308 is 1.E +308, so 1024 particles would be able to break the most secure version of RSA used for bank transactions.
According to our interview, quantum computers have been invented with 4 particles, which are able to factorise 2 to the power of 4 or 16 numbers at a time.