Quantum / gauge field -> Classical limit

This is also why we let phi -> 0 as V->oo, as it represents a situation where the field becomes infinitely large and the interactions between particles are negligible.
  • #1
ansgar
516
1
Hello all quantum nerds! :D

I have a question regarding the "classical" limit of quantum fields, and in particular gauge fields.

When we for instance do a surface integration in QFT, we let phi -> 0 as V->oo

why? this is said in textbooks to correspond to the "classical limit",

and for gauge fields, one let's the field strength tensor F_mu,nu -> 0 which makes the gauge potential go to zero or a gauge transformation of 0.

So why these boundaries in the "classical" limit (V->oo)

Best regards
 
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  • #2
,Quantum nerd #2The classical limit of a quantum field is the limit as the number of particles in the field goes to infinity. The reason we set certain parameters to zero in this limit is because it corresponds to a situation where the interactions between particles are negligible. When the field strength tensor F_mu,nu -> 0, it means that the interactions between particles become weaker and weaker until they no longer have any effect on the system, which is the classical limit.
 

1. What is the quantum-gauge field/classical limit?

The quantum-gauge field/classical limit refers to the transition between the quantum and classical behavior of a physical system. In this limit, the effects of quantum mechanics become negligible and the behavior of the system can be described by classical equations.

2. How does the classical limit emerge from the quantum-gauge field?

The classical limit emerges from the quantum-gauge field through a process called decoherence. This occurs when the interactions between a system and its environment cause the system to lose its quantum properties and behave classically. As the system becomes larger and more complex, the effects of decoherence become more prominent and the classical limit becomes more apparent.

3. What is the role of gauge fields in the quantum/classical limit?

Gauge fields play a crucial role in the quantum/classical limit as they are responsible for mediating the interactions between particles in a quantum system. In the classical limit, these interactions become well-defined and can be described by classical equations of motion.

4. Can the classical limit be observed in experiments?

Yes, the classical limit can be observed in experiments. One example is the double-slit experiment, where a quantum system (such as a photon) exhibits wave-like behavior in its quantum state, but displays classical behavior when observed at the detector screen.

5. What are the practical applications of studying the quantum-gauge field/classical limit?

Studying the quantum-gauge field/classical limit has important applications in various fields, such as quantum computing, where understanding the transition between quantum and classical behavior is crucial. It also has implications in understanding the behavior of fundamental particles and the laws of nature at the smallest scales.

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