In quantum physics experiments, how is their equipment fine-fingered enough to experiment on individual particles? For example in the double slit experiment, how were they shooting exactly a single electron at a time?
In: Physics
Something to note is with things like the LHC, they are not accelerating single pairs of particles. They are accelerating a whole bunch (billions) and waiting for some to invariably collide.
For the double slit experiment, you can control an electron gun by varying the current. Electing guns are related to the technology that powers CRT screens. You basically heat metal which causes electrons to break free (at a rate that is proportional to temperature) and then you use magnetic fields to move them at a desired rate. Go low enough with the current and the electron release is super slow/rare.
It’s fairly straightforward to calculate how many electrons are being emitted, and you can dial that down to the point where, for example, only one electron is emitted per second on average. So you know that any electron will go through the slits and hit the detector long before another electron is emitted.
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In quantum optical labs I’ve seen experiments done it’s all probabilistic (as are most things in quantum), the emitter is designed such that most of the time it doesn’t even fire a photon, rarely fires one and in extremely rare cases, fires two. This makes it easier to be sure that when you do get a result, it was exactly one photon. When it was more than one, there is generally some indication and so you can omit those from your final data. Electrons are probably easier as they are bigger, but my university specialized in optics so I didn’t see any electron setups.
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