Josephson junction

So, you see there are these tiny, tiny bits called atoms and they make up everything around us like air, water, and even you and me! These atoms have things called electrons that move around in them. Sometimes, if we cool these electrons down really, really cold (almost close to 0 degrees Celsius) and put two pieces of metal really close together, some very special things can happen. This special thing is called a Josephson Junction!

A Josephson Junction is like a tiny door in between those two pieces of metal. When the metal electrons get really cold, they start acting really, really strange because they become superconducting. This means they can flow through the metal without any resistance, which is something that doesn't happen normally.

The tiny door (Josephson Junction) lets these superconducting electrons go from one metal to the other. But here's the craziest part - these electrons can do something called "quantum tunneling". It means they can go right through the door without opening it! This is because they are so small they can squeeze through the tiny gaps in between the door and get to the other side.

Scientists use Josephson Junctions to do really cool things like measuring magnetic fields and making really, really fast computers. So, even though they are really tiny, they can do some really big, important things!