Quantum Information for Quantum Cats (2)

What is Quantum Mechanics?

Although you might be totally unaware, everything around you (even including you yourself) are following the law of quantum mechanics. So that means you cannnot really talk about this world without the knowledge of quantum physics. However, you have surely never felt slightest inconvenience for not knowing such exotic theory. That is beacuse, in the daily world of macroscopic scale measured in meter, the quantum mechanics usually is reduced to the familiar classical mechanics that forms the basis of our common sense.

When you start dealing with miniscule particles, as you have to do in so-called nanotechnology, however, the particle sometimes start behaving weirdly revealing its true quantum mechanical characteristics. The truth is that the world we know now would not even exist if these minute particles known as atoms and electrons were to follow the classical mechanics. In other words, the world exist exactly because the atoms and electrons go about in inexplicable quantum fashion. This has been arguably the biggest discovery of the last century, and in fact, of all time, and the discoverers of quantum mechanics - Planck, Bohr, Einstein, Schrodinger, Heisemberg, Dirac - should be equated to the those ancient greats such as Thales, Heracleitos, Epicuros, Platon and Aristoteles.

In typical engineering course for quantum mechanics, you start solving simple problem of Schrodinger eaution immediately. It is true that he Schrodinger equation of course forms the counter piece of quantum mechanics, but it is an equation that describe the dynamics, or the temporary evelution of an object, and even before temporal evolution, the objects exists in very different fashion in quantum mechanics when compared to the classical existence. That different mode of existence of quantum particles are the real source of the power of quantum information, and the Schrodinger equation and its solution under given concrete physical settings itself is of secondary importance.

A quantum particle exists in "quantum states" or simply called states, that have very peculiar characteristics. First amongst these peculiarity is the subtle and indirect relation between the states and observed results. Another peculiarity is the prinple of "linear superposition of amplitudes" that allows quantum particle to exist in two classically incompatible locations and velocities, and also allow them to interfere to each other. This latter peculiarity is usually known under the name of Schrodinger's cat, which is a bit of political incorectness in todays animal-right consciousness.