This description is wrong.
Quantum superposition is exhibited in fact in many directly observable phenomena, such as interference peaks from an electron wave in a double-slit experiment.
— Wikipedia on Quantum superposition
Whatever you observe, it is not a superposition.
If no left-right detector is allowed, the moving-left/right variable is an unobservable. What you observe, instead, is the dot on the final screen.
In other words, the observable is the final position of a particle when it reaches the final screen. And the final screen itself acts as the detector for that observable.
Superposition is unobservable due to the lack of definition (of the distinction between different states) of the corresponding physical variable, due to the fact that no corresponding detector, such as the left-right detector, is allowed in the experimental design.
~ observable events
~ logically unobservable, since not yet defined
~ not yet defined, since logically undefinable
~ logically undefinable, since no corresponding detector is allowed
A superposition state is not an observable state. In other words, it is not a physical state. Then what is the point of considering it?
Although a superposition state is not a physical state, it is a mathematical state that can be used to calculate the probabilities of different possible physical-states/observable-events.
— Me@2022-07-06 06:00:55 PM
2022.07.07 Thursday (c) All rights reserved by ACHK