Andreev reflection
Andreev reflection is a phenomenon that happens when something called an electron (a tiny particle) moves from one material to another. The electron is sent from a material with a higher energy level (called a “high energy material”), to a material with a lower energy level (called a “low energy material”).
When the electron reaches the low energy material, something special happens. Instead of just going in to the low energy material, it reflects back, like it was bouncing off of something. This reflection is called Andreev reflection, and it happens because the electron turns into something called a “hole” which is like an empty space. This hole then moves back to the high energy material. It’s like playing a game of ping-pong. The electron is the ball that goes back and forth between the two materials.
When the electron reaches the low energy material, something special happens. Instead of just going in to the low energy material, it reflects back, like it was bouncing off of something. This reflection is called Andreev reflection, and it happens because the electron turns into something called a “hole” which is like an empty space. This hole then moves back to the high energy material. It’s like playing a game of ping-pong. The electron is the ball that goes back and forth between the two materials.