How do we know that subatomic particles exist in superposition?

Question

How do we know that subatomic particles exist in superposition?

In: 1

Answer 1

The most straightforward answer would refer to a landmark experiment performed in 1801 by Thomas Young referred to as the double slit experiment.

This experiment used subatomic particles of light, or “photons”. In the experiment, individual photons were aimed single file at a partition which had only two openings. Each opening was so small that only one photon could fit through it at a time.

However, the results showed that each single photon passed through BOTH openings simultaneously.

There is more nuance to it but that’s the ELI5 version.