Gauge Transformation Quantum Electrodynamics

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SUMMARY

The discussion centers on the implications of gauge transformation in Quantum Electrodynamics (QED) when analyzing multiple particles in an electromagnetic field. The Hamiltonian for a system of two particles is expressed as H=\dfrac{(p_{1}-\frac{e}{c}A)^2}{2m} +\dfrac{(p_{2}-\frac{e}{c}A)^2}{2m} +e \phi, maintaining the condition \vec{\nabla } \times \vec{A} =\vec{B}. The author explores the possibility of using different gauges for each particle while observing that the equations of motion remain unchanged under the same gauge. This raises questions about the symmetry of the Hamiltonian when multiple gauges are applied.

PREREQUISITES
  • Understanding of Quantum Electrodynamics (QED)
  • Familiarity with Hamiltonian mechanics
  • Knowledge of gauge theory and electromagnetic fields
  • Proficiency in deriving equations of motion from Hamiltonians
NEXT STEPS
  • Investigate gauge invariance in Quantum Field Theory
  • Study the implications of gauge transformations on particle interactions
  • Learn about the role of symmetry in Hamiltonian systems
  • Explore the Heisenberg equations in the context of multiple particles
USEFUL FOR

The discussion is beneficial for theoretical physicists, quantum mechanics researchers, and students studying Quantum Electrodynamics, particularly those interested in gauge theories and their implications on particle dynamics.

Juan Carlos
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It's well known when if we are working on problems related to particles in presence of an electromanetic field, the way we state the problem can be done using the next Hamiltonian:
H=\dfrac{(p-\frac{e}{c}A)^2}{2m} +e \phi where the only condition for A is: \vec{\nabla } \times \vec{A} =\vec{B}
So we have this "gauge freedom" under (of course) the above condition .
What happens when are studying two or more partcles in presence of the electromagnetic field.

Naturally:
H=\dfrac{(p_{1}-\frac{e}{c}A)^2}{2m} +\dfrac{(p_{2}-\frac{e}{c}A)^2}{2m} +e \phi where the only condition for A is: \vec{\nabla } \times \vec{A} =\vec{B}

The question is: can we relax the condition of one unique gauge for all the particles?

Just saying:
can we select two different gauges? obviously with the condition : \vec{\nabla } \times \vec{A} =\vec{B}

I've been working on this, I satetd two different gauges and I can say that there is no difference in terms between the equations of motion having the same gauge. (Hamilton)

In particular I've done the same for the correspoding quantum problem obtainig the heisemberg equations, having the same result: no difference.

I'm interested on the quantum problem because having two different gauges could provoque loosing the symmetry of a Hamiltonian given.
 
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When you fix a gauge you do that for the electromagnetic potential, which is only one in your problem. This shouldn't be influenced by how many particles you have. What do you mean by fixing two different gauges?
 

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