So you mention long-range. From the literature, I saw that CDW/SDW is described as the "order parameter" in Landau-Ginzburg model. What kind of symmetry breaking is involved? Can I say translational symmetry? Which reference do you suggest if I want to understand more about its phenomenological...
And does anybody know about charge density wave (CDW) and spin density wave (SDW)?
My question is... what is the mechanism that induces the instability of CDW and SDW?
Despite the sameness of the mathematical structure even after some real-dynamics of the two isolated condensates, I would say they are still not entangled because the state of the composite system is still separable into two subsystems of BEC.
I think entanglement is possibly induced by coupling.
It was observed that stripe phases appear in some high-temperature superconductivity and it is believed to be related to strongly-correlated electron system. Is the mechanism of the formation of stripe phase completely known? Does it appear in non-superconducting systems as well?
I understand that unwinding the field configurations to trivial topology requires an infinite amount of energy, or in other words we can say a continuous deformation of the field from one topology to another is impossible. But is there a physical reason that leads to this consequence? I do not...
In a quantum fluid, we know that it is difficult to add or destroy a vortex because of the conservation of angular momentum.
Suppose now we have a skyrmion replacing a vortex. What the conservation law is skyrmion associated with?
Mermin-Wagner theorem tells you that if there is a long-range-order (existence of BEC) in two-dimensional systems, the fluctuations will drive the system to somewhere else, destroying the condensate. Yes, as puzzly said, it is the long-wavelength phonon that destroys the coherence of the...
I agree with saaskis that there should be no second quantization here, at least for the theory of ferromagnets here. And M(x), as saaskis said, is the spatial average of magnetization at a point, which can be derived from a more microscopic model with [tex]\psi[\tex] and [tex]\psi^{\dag}[\tex]...
The first one is basically a process between photons and a free electron or a free nucleus.
The second one is a quantum mechanical process between photons and an atom. When you say the energy difference between states of electron, I think you mean energy difference between states of the ATOM...
Q1: I am not sure if i understand your question, but Sz means the spin in z-direction in real-space. but of course, it is up to the definition of z-axis in your system.
Q2: You can operate (S_1+S_2)^2 on the state you have to see if it gives an eigenvalue 1*(1+1). (This is actually a tricky...
Actually what I said is also true for statistical mechanics and it is the magnetic susceptibility of the ferromagnet. IN QFT, \xi is the screening length of the Yukawa potential, but in statistical mechanics, it is the correlation length of the fluctuations.
I have the book at hand now. I don't...
I am not at home right now and hence I cannot check Huang's book at the moment. Do you mean Kerson Huang's "Statistical Mechanics"?
To your question, my answer is yes.
And it is true that for paramagnet or the longitudinal component of a ferromagnet (true for the transverse component but...