- #1
Daniel Petka
- 117
- 11
- TL;DR Summary
- If a very short (laser) pulse attenuated to single photon intensity passes through a narrow band pass filter, do the photons get detected at random times?
Here is my thought experiment: Let's say I attenuate a very short laser pulse to single photon intensity. Due to the uncertainty principle, I know the time of arrival of the photons, but not their energy. So let's reverse that by splitting the pulse in its spectral components with a diffraction grating and passing the spectrum through a slit. The photons that pass through the slit will have a defined energy, but not a defined time of arrival, because each new photon arrives on a random spot and so it's also random if it passes through the slit. This seems logical (kind of). But now let's pass the pulse directly through a narrow band pass filter instead. The photons should still appear randomly. Is that true? If yes, it's extremely counter intuitive. It's as if the band pass filter can delay a photon randomly. How does this happen, what's going on here physically? It has to be true because, well, Fourier Transform, but I don't get why.