# How does the double slit experiment take us to superposition?

1. Nov 4, 2015

### RayEddy

Pretty obvious that measuring at the double slits neutralizes whatever action or reaction is creating the wave pattern. But why the quantum leap to assuming superposition?

What other configurations have been tested or were there just slits used? What about a round hole or holes, an “X” slit or asterisk shaped slit? Stacked slits?

2. Nov 4, 2015

### bhobba

Last edited: Nov 5, 2015
3. Nov 4, 2015

### Staff: Mentor

Superposition is a general mathematical concept that applies to the solutions to a large class of differential equations - the ones that have the property that if $A$ and $B$ are both solutions, then the superposition $(A+B)$ is also a solution. Schrodinger's equation, the one that describes the behavior of quantum systems, is one of these equations.

Thus, superposition was not a wild leap inspired by the double-slit experiment; it's pretty much baked into the mathematical formalism of QM. The wild leaps came earlier, with the series of brilliant intuitions that led physicists to try matching that particular mathematical formalism to their experiments. (These wild leaps have since been more formally justified, as once we knew what the answer should be it became a lot easier to derive it properly).

4. Nov 5, 2015

### ZapperZ

Staff Emeritus
I think you are missing the point. You are focusing on the wrong thing.

It is not the "slit geometry" that is important here. It is the available path for the photon (or electron, or any quantum object).

I had just linked this paper in another thread, and it might be useful for you to read it:

http://departments.colgate.edu/physics/research/Photon/root/ajpbs02.pdf

Zz.

5. Nov 7, 2015

### zonde

Nice paper. But one thing is puzzling me, in chapter about two-photon interference it says:
"If phase shifters are placed in the arms of the interferometer and the output photons are detected in coincidence, an interference pattern will be observed in the coincidences even though none is observed in the counts of the individual detectors."
I think it's wrong. You observe HOM dip not HOM envelope, right.

6. Nov 7, 2015

What is HOM?

7. Nov 7, 2015