ELI5: Explain Like I'm 5

Quantum fidelity

Imagine you have a toy that has two colors - red and blue. Let's say you have another toy that looks the same, but you don't know if it's red or blue. Quantum fidelity is like checking how much the two toys match.

In the quantum world, we have something called a quantum state. This state describes the state of a quantum object, like an electron or a photon. Let's say you have two quantum states. Quantum fidelity is like checking how close these two states are to each other.

If the two states are very similar, they have high fidelity. If they are very different, they have low fidelity. Think of it like trying to match two puzzle pieces. If they fit perfectly, they have high fidelity. If they don't fit, they have low fidelity.

Scientists use quantum fidelity to measure how well quantum systems are functioning. It helps them understand if their quantum systems are working correctly or not. Think of it like checking if your toys are both red or both blue. If they are, you know everything is okay. If not, you'll have to check again!