Wave packet experimental detection

In summary, the "collapse" is a questionable concept and not really needed for the physical interpretation of quantum theory.
  • #1
VVS2000
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Are there any experimental setups that verify the wave packet dynamics we work with in quantum mechanics?
It just came up in my QM class while we were discussing and even my teachers could'nt figure it out
I know the wave function "collapses" when a measurement is made but still not satisfied with it
 
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  • #2
Rightfully so. The "collapse" is a very questionable concept and not really needed for the physical interpretation of quantum theory. It's obvious that it depends on the specific measurement made on the measured object, which state this object takes after a measurement has been made. E.g., if you detect a photon in the usual way using the photoelectric effect (e.g., using a CCD cam or a photoplate) this photon gets absorbed and is thus gone for good.

It's of course very difficult to measure "wave-packet dynamics". An example is this:

https://doi.org/10.1103/PhysRevLett.72.3783
https://pure.uva.nl/ws/files/2978244/478_5187y.pdf
 
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  • #3
VVS2000 said:
I know the wave function "collapses" when a measurement is made
Exactly what "collapse" means depends on which QM intepretation you adopt. Note that discussion of particular interpretations belongs in the interpretations subforum.

In the absence of any particular interpretation, "collapse" is just the mathematical procedure we use to update our model when we know the result of a measurement, and no assertion is made at all about what, if anything, "actually happens".
 
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  • #4
The "collapse" is simply the update of the state after the interaction with a "filter". This idealized "von Neumann filter measurements" are very rarely achieved. An example is the Stern-Gerlach experiment for measuring and preparing spin states of an atom (in the original experiment silver atoms). Here the atom is send through an inhomogeneous magnetic field. According to quantum mechanics the atom moves in different discrete directions depending on the value of the spin component in direction of the magnetic field. Then the position (or momentum) of the atom is entangled with this value of the spin component, i.e., you can just block all atoms which are at positions referring to the spin value you don't want, and thus all atoms going through this filter have a determined spin component in direction of the magnetic field, and you describe them by a corresponding wave function which is a eigenstate of this spin component with the eigenvalue you filtered out.
 
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  • #5
PeterDonis said:
Exactly what "collapse" means depends on which QM intepretation you adopt. Note that discussion of particular interpretations belongs in the interpretations subforum.

In the absence of any particular interpretation, "collapse" is just the mathematical procedure we use to update our model when we know the result of a measurement, and no assertion is made at all about what, if anything, "actually happens".
yeah I know, that's why I told I was not satisfied with that answer
 
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What is a wave packet?

A wave packet is a localized, transient wave that represents a group of waves with different frequencies and wavelengths. It is used to describe the behavior of particles in quantum mechanics.

How is a wave packet experimentally detected?

Wave packet detection involves using a detector, such as a photodetector or a screen, to measure the intensity or position of the wave packet. This can be done by observing the interference pattern created by the wave packet or by directly measuring the properties of the particles in the packet.

What is the significance of wave packet detection in quantum mechanics?

Wave packet detection is important in understanding the behavior of particles at the quantum level. It allows scientists to study the properties of particles, such as their position and momentum, and to make predictions about their future behavior.

What are some challenges in wave packet detection?

One challenge in wave packet detection is maintaining the coherence of the wave packet, as it can quickly disperse and lose its localized nature. Another challenge is the uncertainty principle, which states that it is impossible to know the exact position and momentum of a particle simultaneously.

How does wave packet detection contribute to our understanding of the universe?

Wave packet detection is a fundamental tool in quantum mechanics, which is essential for understanding the behavior of particles and the nature of the universe. It allows us to study the behavior of particles at the smallest scale and make predictions about their behavior in various physical systems.

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