Quantum mechanics
To understand the experiments on this site it is good to clarify some fundamental concepts of quantum mechanics.
Unfortunately, the explanations found online on these topics are approximate and those in school books are even worse. So we recommend mental cleansing, eliminate all the misleading information you have heard so far and start from a safe and well explained basis.
In addition to the informative videos of prof. Damiano Anselmi, you can find excellent explanations by Massimiliano Sassoli de Bianchi on this channel.
We recommend starting with these lessons:
– Quantum superposition
– The (poor man) Schrodinger's cat
– What is the mystery of quantum entanglement?