What is the Green inverse function for a given propagator?

  • Thread starter eljose
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In summary, the conversation discusses the construction of the Hamiltonian using the propagator G(x,t)=\frac{1}{e^{xt}+1} as well as the use of Fourier Transforms to find the Fourier transform of the desired operator. It is mentioned that this topic is typically covered in a QFT or QM course. The suggestion is made to use z=1+exp(xt) and Poisson's equation to work backwards.
  • #1
eljose
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given the propagator:

[tex]G(x,t)=\frac{1}{e^{xt}+1}[/tex]

and knowing that HG(x,t)=d(x-t) with d the "delta" function and H the Hamiltonian,then how could we construct (knowng G(x,t))the Hamiltonian?...

I one work i heard about the Green inverse function, how is it calculated?
 
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  • #2
Well that is quite some work ? Are you expected to do that all on your own ? Normally you should have seen this in your QFT-course or your QM-course. It is an integral equation that you'll need to solve

regards
marlon
 
  • #3
I think you can use Fourier Transforms to find the Forurier transform of the operator you're looking for.
 
  • #4
bigubau said:
I think you can use Fourier Transforms to find the Forurier transform of the operator you're looking for.

Well, that's not all there is to it.

The OP must have seen some analoguous systems in his/her QFT-course, otherwise i really don't see the point of us starting to discuss this topic

marlon
 
  • #5
It's Jose.He's a "he".It doesn't seem like QFT to me...
 
  • #6
bigubau said:
It's Jose.He's a "he".It doesn't seem like QFT to me...

it has to be QM or QFT, you cannot tell which one based upon these data

marlon
 
  • #7
Try setting 1+exp(xt) = z. Then G=1/z, and work backwards from Poisson's Eq in z.

Regards,
Reilly Atkinson
 

1. What is a propagator?

A propagator is a term used in physics and mathematics to describe a function or operator that describes the evolution of a system over time. It is often used in quantum mechanics to calculate the probability of a particle moving from one point to another.

2. What is the problem with propagators?

The problem with propagators is that they can be difficult to calculate or solve, especially in complex systems. This is because they often involve multiple variables and complex mathematical equations.

3. How is the problem with propagators addressed?

Scientists and mathematicians use various techniques and approximations to solve or simplify the problem with propagators. These include perturbation theory, numerical methods, and approximations such as the WKB method.

4. Can the problem with propagators be avoided?

In some cases, the problem with propagators can be avoided by using alternative methods of calculation. For example, instead of calculating a propagator, one could use a path integral approach to solve a problem in quantum mechanics.

5. Are there any current research developments related to the problem with propagators?

Yes, there are ongoing research efforts to improve our understanding of propagators and find more efficient ways to calculate them. This includes developing new mathematical techniques and using advanced computational methods.

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