The discussion centers on the relationship between Quantum Field Theory (QFT) and many-body Quantum Mechanics (QM), exploring whether they are equivalent or distinct frameworks. Participants examine various aspects such as instantons, topological phenomena, quasiparticle excitations, and the implications of particle number conservation, with a focus on theoretical and conceptual considerations.
Participants express differing views on the equivalence of QFT and many-body QM, with no consensus reached. Some argue for equivalence under specific conditions, while others highlight significant distinctions and limitations.
Participants note limitations in their arguments, including the need for specific references to support claims and the speculative nature of some points raised. The discussion reflects a variety of interpretations and uncertainties regarding the relationship between the two theories.
I agree, this is what it seems. Nevertheless this is what I've read. I'm actually curious if qft can be the result of the missing information. There is a certain analogy with the ordinary information transfer. Quantum fields look like a superposition of causal sets.vanhees71 said:QFT formulation is superior in all cases, where you have particle creation and destruction processes and equivalent to (many-body) QM if this is not the case.
Can you give more details on this or provide a reference?Fractal matter said:I agree, this is what it seems. Nevertheless this is what I've read. I'm actually curious if qft can be the result of the missing information. There is a certain analogy with the ordinary information transfer. Quantum fields look like a superposition of causal sets.
What exactly are you interested in ? I don't remember the title of the 1st paper. As for the missing information there are quite a few. For example: Quantum States as Ordinary Information - https://www.mdpi.com/2078-2489/5/1/190 I don't know the details, just in general.Joker93 said:Can you give more details on this or provide a reference?
Can you give an example please ? I'm interested in all the cases in which the effective theory doesn't have quasiparticles.Demystifier said:Some effects may be described by topological effective field theory, in which case it may not have quasiparticle excitations.
All topological field theories lack propagating degrees of freedom and hence (quasi)particles. An example of topological field theory is Chern-Simons theory. In condensed matter, it plays a role in a description of quantum Hall effect (see e.g. https://arxiv.org/abs/1606.06687). Roughly speaking, in the quantum Hall effect the EM field interacts with matter in such a way that the effective dressed EM field cannot propagate through the material, so the dressed EM field does not have dressed photon excitations.Fractal matter said:Can you give an example please ? I'm interested in all the cases in which the effective theory doesn't have quasiparticles.