Superposition and Quantum Entanglement

In this, the last chapter in the ‘How Small Is It’ video book, we’ll cover quantum superposition and quantum entanglement. We’ll also finish the work on the double slit experiment we covered in our first chapter on ‘The Microscopic’.  We’ll be using electron spin and polarized light in most of our examples. Beginning with light, we’ll cover exactly how polarization works. Then we’ll use it to illustrate how we know which slit light went through in the double slit experiment. This illustration will highlight the nature of quantum linear superposition. As part of this we’ll take a look at Schrodinger’s Cat.

With superposition in hand, we’ll cover how these superposition states can become entangled across multiple particles. We’ll start with some classical behavior associated with water waves and spinning coins. Then, using electron spin, we’ll illustrate entanglement. We’ll follow that with Einstein’s problem with ‘spooky action at a distance’. We’ll cover several experiments both thought (from John Bell) and real as quantum physics progressed in its ability to manage the quantum world. We’ll see what a ‘ghost image’ is and how it was used to show Einstein was wrong. As part of this segment, we’ll cover the ‘Quantum Eraser’ experiment.

We’ll end with a look at Quantum Computers. Here we cover how electrons are controlled in such a way that they can be put into and taken out of a superposition state at will. And in addition, they can be managed into and out of entangled states. This ability enables quantum computing.