Reconstruction of potential V(x)

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SUMMARY

The discussion centers on the reconstruction of the potential V(x) from the trace of the Hamiltonian operator, specifically Tr(h(Ĥ)). It is established that while the trace provides information about the spectrum of the Hamiltonian, it does not uniquely determine the potential V(x). For example, in the case of the Harmonic Oscillator, despite having the trace expression, one cannot conclude that V(x) takes the form of ax² without additional information, such as the eigenfunctions or the exact Hamiltonian form.

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  • Understanding of Hamiltonian mechanics and operators
  • Familiarity with spectral theory and eigenfunctions
  • Knowledge of trace operations in quantum mechanics
  • Basic concepts of potential energy in quantum systems
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This discussion is beneficial for physicists, quantum mechanics researchers, and students studying Hamiltonian systems, particularly those interested in potential reconstruction and spectral analysis.

zetafunction
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the idea is, let us suppose we know the trace

[tex]Tr(h(\hat H ))= \sum_{n=0}^{\infty}h(E_n )[/tex]

here 'h' can be a real or complex exponential of the form exp(-ax) and 'H' is the usual Hamiltonian operator

[tex]H=p^2 + V(x)[/tex]

what information about the spectrum of Hamiltonian would i need in order to obtain V(x) ??

for example: for the Harmonic Oscillator in Planck's unit so h=1 and w=1 i have that

[tex]\sum _{n=0}^{\infty} exp(-s(n+1/2))= \frac{exp(-s/2)}{1-exp(-s)}[/tex]

then from the expression above could i conclude that potential goes like [tex]V(x)=ax^{2}[/tex]
 
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??The answer is no. In general, it is not possible to determine the potential V(x) from the trace Tr(h(\hat H )). The trace includes information about the spectrum of the Hamiltonian, but does not contain enough information to uniquely determine the potential. To do this, one would need additional information, such as the eigenfunctions of the Hamiltonian or knowledge of the exact form of the Hamiltonian.
 

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