Bloch sphere

A Bloch sphere is like a ball that helps us understand how the smallest things in the world, called quantum bits or qubits, work. It helps us see how these qubits can move around and change, sort of like how you can play with a ball and make it spin or move in different ways.

Imagine you have a ball and you can hold it in your hand. But this ball is special because it can do things that normal balls can't do. It can change colors and move around in really weird ways.

Now let's pretend that this ball is a qubit. When you hold it in your hand, it can be in two different states. It's like a light switch that can be either on or off.

But the Bloch sphere helps us understand that qubits aren't just on or off. They can actually be in a whole bunch of different states at once, sort of like how you can mix different colors together and make new colors.

The Bloch sphere lets us see how qubits move and change over time. It's like a map that shows us where the qubit is and where it's going. We can use this map to help us do all sorts of cool things, like send secret messages and solve really hard math problems.

So, in summary, a Bloch sphere is a special ball that helps us understand how tiny things called qubits move and change. It's like a map that lets us see where the qubits are and where they're going, and it helps us do all sorts of fun and useful things.