The use in solving the Klein Gordon equation?

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SUMMARY

The discussion focuses on the interpretation and application of the Klein-Gordon equation in quantum field theory (QFT). It clarifies that the equation should be viewed as describing a field operator responsible for particle creation and annihilation, rather than a traditional wave function. The conversation emphasizes that solving the Klein-Gordon equation yields a scalar function, but the interpretation of this solution as a field operator is crucial. Additionally, the discussion raises questions about the initial and boundary conditions relevant to the Klein-Gordon equation.

PREREQUISITES
  • Understanding of quantum field theory (QFT)
  • Familiarity with the Klein-Gordon equation
  • Knowledge of wave functions and their quantization
  • Basic concepts of particle creation and annihilation operators
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  • Study the interpretation of the Klein-Gordon equation in quantum field theory
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  • Research initial and boundary conditions for the Klein-Gordon equation
  • Explore the role of scalar fields in quantum field theory
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Physicists, quantum field theorists, and students studying advanced quantum mechanics who seek to deepen their understanding of the Klein-Gordon equation and its implications in particle physics.

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I've done some reading on quantum field theory, and I went over how when Schrödinger first derived this equation, he discarded because it yielded negative energy solutions, negative probability distributions and it gave an incorrect spectrum for the hydrogen atom. The book then went on to state that it was later discovered that the main flaw with the Klein Gordon equation was its interpretation rather than the equation itself. Rather than interpreting the solution φ as a wave function, apparently φ was promoted to being an operator. Specifically, it is apparently a field responsible for the creation and annihilation of particles.

Now here is where my question comes in. Sorry if it seems too basic:

When I solve the Klein-Gordon equation am I actually solving for the field, or am I just solving an equation that is now useless and serves no other purpose due to the latter interpretation of the equation and to the latter introduction of the Dirac equation? Here is why I ask this:

Solving the Klein Gordon equation is quite similar to solving Schrödinger's equation. The solution (just like in the case with the wave function in the Schrödinger equation) just comes out to be some scalar function of x, y, z, and t. While I know that wave functions are quantized in this manner, I don't know if a field is supposed to be quantized as a scalar function or some other mathematical object such as a matrix or some higher rank tensor.

That is why I ask you all if I am really solving for the quantum field by solving the Klein Gordon equation or if the field must be calculated by some other means.

(On another note, what kind of initial and boundary conditions would the Klein Gordon equation have?)
 
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In QFT, a spin-zero particle is an excitation of a scalar field. When interactions are neglected, this scalar field (which is an operator that acts on states) satisfies the KG equation (in the Heisenberg picture of QM).
 

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