I wondered exactly the same thing (see my other comment). However, I am not sure if they can actually film single photons. My school physics are a bit rusty, but iirc, quantum effects will not be relevant if you actually fire a light "impulse" consisting of many, many photons. However, as I have asked in my previous comment, it would be interesting if you could actually see the light impulse being "split up" and interfering with itself.
You can detect single photons. There are off the shelf detectors for available for experimenting with photon entanglement and parametric down conversion. We had one at my university.
Yes, this is called a "quantum non-demolition measurement" and has actually been done. One technique is to use highly excited atoms (Rydberg atoms) which are extremely sensitive to external electric fields. In this way, the field caused by a single photon can be detected without absorbing the photon. There is a famous paper from Serge Haroche's group where they used this method to detect the presence of single microwave photons in a superconducting cavity (https://www.nature.com/articles/nature05589).
However, the measurement still collapses the wavefunction of the system. Performing a QND measurement to determine which slit the photon takes in a double-slit experiment simply destroys the interference pattern.
Curious, what is "the field generated by a single photon" made of? Off hand, I think the force carrier for EM fields is the photon no? So, the photon is emitting other photons (virtual I think?) then?
Kinda, no. By observing a photon you perturb the system, you wouldn't get a result for what that photon would have done had it not been perturbed. AIUI if you detect the photon then it interacted with some part of your sensing apparatus, so it didn't then go on to do what it should have. Thus we're left to look at the aftermath and impute the situation that produced it.
