In the atom interferometer experiment of Figure 38.13, laser-cooling techniques were used to cool a dilute vapor of sodium atoms to a temperature of 0.0010 K=1.0 mK. The ultracold atoms passed through a series of collimating apertures to form the atomic beam you see entering the figure from the left. The standing light waves were created from a laser beam with a wavelength of 590 nm.

d. Because interference is observed between the two paths, each individual atom is apparently present at both point B and point C. Describe, in your own words, what this experiment tells you about the nature of matter.

Video transcript

Hello, fellow physicists today, we're gonna solve the following practice problem together. So first off, let us read the problem and highlight all the key pieces of information that we need to use. In order to solve this problem in a double slit experiment. A beam of electrons is directed towards a barrier with two slits when the electrons pass through the slits and hit a screen behind the barrier, an interference pattern is observed as a result. What does this experiment reveal about the nature of electrons? So that's our goal. Our angles are trying to figure out what does a double slit experiment reveal about the nature of electrons. And that's our final answer we're ultimately trying to solve for is what does it reveal like an explanation for what it reveals? So with that in mind, let's read off our multiple choice answers to see what our final answer might be. A is electrons behave only as particles B is electrons behave only as waves C is electrons exhibit both particle like and wave like behaviors. And D is the behavior of electrons cannot be determined from this experiment. OK. So first off, we can solve this problem in three simple steps. So our first step is we need to recall and note that the double slit experiment demonstrates that electrons which are typically considered as particles will also have wave properties. We also need to recall and note that the experiment demonstrates that electrons exhibit bolt particle like and wave like properties. And this is due to the fact as we should recall that when electrons pass through the slits, they will produce an interference pattern on the screen, which is characteristic of waves. This therefore indicates that electrons can behave as waves and interfere with each other. Our second step is we need to rip fall that when a measurement is made to determine which slit an electron will pass through the wave function will collapse. And the electron will therefore behave as a particle passing through one slit or the other. And this will result in the disappearance of the interference pattern, which will therefore demonstrate the role of obs observation in quantum mechanics. And thirdly, the observation of an interference pattern can indicate that each electron will behave like a wave that can travel along multiple paths simultaneously. And this is something we should be able to recall via the conceptual physics that you should have learned in your textbook and moving right along here. This will therefore imply as we should recall that electrons will exist in multiple states at once like a superposition state until it is measured. So finally, therefore, this means that the experiment will underscore the quantum nature of matter. So therefore, as a summary, we need to note that in a double slit experiment with electrons, it will reveal that electrons will have a dual nature behaving both as particles and as waves. So this is also known as a wal as they perform because they behave both as particles and as waves. So you probably heard this phrase a WAV and this is because an electron behaves like a wave and a particle. So therefore, this means that our final answer has to be the letter C electrons exhibit both particle like and wave like behaviors. So this problem is very easy to solve as long as you have a strong understanding of the conceptual physics behind a double slit experiment. So once again to quickly highlight since this is all, since we know that this is a WAV equal because it behaves both as a particle in a wave, it underscores the core principles of quantum mechanics including the wave particle duality superposition probability and the impact of measurement on quantum systems. And that's it. That's how you solve for this problem. Thank you so much for watching. Hopefully, that helped and I can't wait to see you in the next video. Bye.