A Short Introduction to Quantum Theory
To understand, why terms such as ‘Quantum Theory’, ‘Quantum Mechanics’ or ‘Quantum Physics’ were introduced and why these fields of scientific research had an astonishing big impact on Cryptography, we need to go back to the year 1799.
In 1799 the English polymath Thomas Young carried out an experiment, in which he sent light through 2 narrow slits and expected to see two bright stripes on a screen, that he had positioned in front of the slits at some distance. Instead he observed that the light fanned out from the slits and formed a pattern of light and dark stripes on the screen.
The explanation of this phenomenon came into his mind some time later, when he observed several ducks at a pond. The ducks were swimming behind each other, each producing a trail of small ripples and it was obvious that those ripples were somehow interfering with each other. If two wave peaks arrived at a spot simultaneously, then the result was an even higher peak whereas two troughs seemed to produce an even deeper trough. Therefore Young assumed, that light was some kind of wave and that the different stripes on his screen were the result of some interaction of the light rays. The ducks gave Young a deeper insight into the nature of light and inspired him to publish his masterpiece “The Undulatory Theory of Light”.
The idea of so called Superposition was introduced.
Please consult Wikipedia.org to find out more about Quatum Mechanics: