The discussion centers on the equivalence of Quantum Field Theory (QFT) and many-body Quantum Mechanics (QM). Key points include that QFT can capture instantonic solutions and topological phenomena, while many-body QM has limitations in these areas. The conversation highlights that many-body QM is effectively a subset of QFT, particularly in the context of nonrelativistic systems, but struggles with complex topologies and certain condensed matter systems, such as strange metals. The participants reference authoritative texts, including Weinberg's QFT volumes and Hartnoll et al.'s "Holographic Quantum Matter," to substantiate their claims.
PREREQUISITESPhysicists, particularly those specializing in quantum mechanics, condensed matter physics, and theoretical physics, will benefit from this discussion. It is also relevant for researchers exploring the nuances between QFT and many-body QM frameworks.
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.