ELI5: Explain Like I'm 5

Bloch state

Hey there little one! A Bloch state is like a special kind of recipe for making a wave. Imagine you have a long piece of material, like a rope, and you want to make waves in it. If you shake one end of the rope, you'll see waves travel down the rope.

Now let's pretend the rope is made up of tiny boxes stacked on top of each other. Each box represents a point in space and time where the wave can be measured. A Bloch state is like a special recipe for making these waves, where we use some basic ingredients to create a wave that looks really cool.

But what are these ingredients? Well, first we need to know something called a lattice. A lattice is like a grid that repeats in space. For example, if we have a line of boxes and we repeat that line over and over again, we'll get lots of lines side by side. That's a lattice!

Now when we make a wave, we use something called a k-vector. Think of this as the direction in which we want the wave to move. It's like pointing your finger in a certain direction.

With our lattice and k-vector ingredients, we can create a Bloch state recipe. This recipe tells us how to make the wave so that it repeats itself perfectly, like a pattern. It also lets us see how the wave will behave when it hits different materials or obstacles.

So, in short, a Bloch state is like a recipe for making waves using some basic ingredients like a lattice and a k-vector. This recipe helps us understand how the wave behaves and repeats itself in space. I hope that helps!