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20
votes
2answers
1k views

What is a phonon?

I am trying to understand intuitively what a phonon is, but for the moment I find it quite difficult (having a limited background in quantum mechanics, an undergraduate course in non-relativistic QM). ...
18
votes
5answers
4k views

Are W & Z bosons virtual or not?

W and Z bosons are observed/discovered. But as force carrying bosons they should be virtual particles, unobservable? And also they require to have mass, but if they are virtual they may be off-shell, ...
18
votes
3answers
1k views

Are elementary particles actually more elementary than quasiparticles?

Quarks and leptons are considered elementary particles, while phonons, holes, and solitons are quasiparticles. In light of emergent phenomena, such as fractionally charged particles in fractional ...
9
votes
3answers
670 views

Phonon carries zero spin. Why?

photons and phonons both have polarization, we attribute spin 1 for photons but spin 0 for phonons. Why?
9
votes
1answer
105 views

Quasiparticles in Bohmian mechanics

My questions are about de Broglie-Bohm "pilot wave" interpretation of quantum mechanics (a.k.a. Bohmian mechanics). Do quasiparticles have any meaning in Bohmian mechanics, or not? Specifically, is ...
7
votes
2answers
1k views

How to get an imaginary self energy?

The Lehman representation of the frequency-dependent single particle Green's function is $$G(k,\omega) = \sum_n \frac{|c_k|^2}{\omega - E_n + i\eta}$$ where $n$ enumerates all the eigenstates of the ...
5
votes
2answers
1k views

What is the difference between a photon and a phonon?

More specifically, how does a wave-particle duality differ from a quasiparticle/collective excitation? What makes a photon a gauge boson and a phonon a Nambu–Goldstone boson?
5
votes
2answers
2k views

The Spectral Function in Many-Body Physics and its Relation to Quasiparticles

recently, I stumbled accross a concept which might be very helpful understanding quasiparticles and effective theories (and might shed light on an the question How to calculate the properties of ...
5
votes
2answers
260 views

Naive questions on Goldstone modes and a possible duality relation?

For example, let's consider a 1D spin-1/2 ferromagnetic (FM) Heisenberg chain $H=-J\sum_{i=1}^{N}\mathbf{S}_i\cdot\mathbf{S}_{i+1}$ with periodic boundary conditions. Now we want to study its low ...
5
votes
1answer
120 views

Can anyons emerge from momentum-space other than spatial dimensions?

So far in condensed matter physics, I only know anyons(abelian or nonabelian) can emerge as quasiparticles in 2D real-space. But is there any possibility to construct anyons in momentum-space ? And ...
4
votes
2answers
291 views

Higgs boson and quasiparticles

Do we know exactly the difference between particles and quasiparticles? Is Higgs boson a particle or a quasiparticle? I ask this because if I understood well, Higgs boson created by a spontaneaous ...
3
votes
1answer
79 views

How do we determine the statistics and spin of quasi-particles?

I am considering the Heisenberg XXZ model at the moment. In the literature it says that (in the $J\Delta\rightarrow\infty$ limit, i.e. the ferromagnetic Ising regime) one can either view low-energy ...
3
votes
2answers
316 views

When is quasiparticle same as elementary excitation, and when is not?

Can anyone shed light on the comparison between these two concepts?
3
votes
1answer
193 views

A naive question on the Quantum Hall Effect(QHE) and the confinement in gauge theory?

The non-interacting 2D lattice QH system is described by the Hamiltonian $H=\sum t_{ij}e^{iA_{ij}}c_i^\dagger c_j+H.c$ My confusion is: Does this imply that the $2D$ lattice QHE is described by the ...
3
votes
1answer
547 views

Phonons, rotons, and maxons

What are phonons, rotons, and maxons, and what does their dispersion curve have to do with superfluidity? I understand that they are quasiparticles, but I'm not entirely sure what that implies. Are ...
3
votes
2answers
544 views

How does Bloch's theorem generalize to a finite sized crystal?

I would be fine with a one dimensional lattice for the purpose of answering this question. I am trying to figure out what more general theorem (if any) gives Bloch's theorem as the number of unit ...
3
votes
0answers
221 views

what interactions would take place between a free proton and a dipolariton?

What interactions can be expected to take place between a free proton and a dipolariton, (a) at high energies and (b) at lower energies? A dipolariton is a bosonic quasi-particle mentioned in a ...
2
votes
1answer
66 views

What is the first paper to report observations of polaritons?

I am seeking references to the first articles regarding the observation of polaritons.
2
votes
1answer
36 views

Rigorous distinction between quasiparticles and collective excitations

I would like to hear your opinion on the question whether there is an accepted distinction between both concepts in condensed matter physics. I would tend to use the word quasiparticle for dressed ...
2
votes
0answers
132 views

Derivation of existence of energy band gap in semiconductor (solid State)

I am looking for both a mathematical and a physical reason for energy band gap in metals. For Physical reason, I was told that at each reciprocal lattice, you could have Bragg scattering, that would ...
2
votes
0answers
109 views

Phonon-polariton literature resources? [closed]

What is a good resource for studying phonon-polaritons?
2
votes
0answers
98 views

What is Z3 exciton?

I am searching and studying excitons and I confronted with a term named Z3 exciton. What is it? And what is its difference with, for instance Z1 or Z2 exciton?
1
vote
3answers
65 views

Excitons in metals-do they exist?

Recently I red an article "Surface Enhanced Fluorescence". It is a topical review by Emmanuel Fort and Samuel Gresillon. Here it is: ...
1
vote
1answer
74 views

Can excitons be understood in terms of classical quantum physics?

From what I understand, an exciton is an electron-hole pair in a semiconductor that exists in a bound state (through the electrostatic potential). I have seen it stated that this pair behaves in a way ...
1
vote
0answers
22 views

Is it possible for quasiparticles to form charge density wave of quasiparticles?

What if the quasiparticle has fractional charge? -----UPDATE------ For example, 1d kink has e/2 charge, if view kink like electrons in 1d (we know there is 1d charge density wave of electrons), is ...
1
vote
0answers
18 views

quasiparticles resembling monopole energy generator

Is it possible using quasiparticles that superficially resemble monopoles to make a generator providing a sustainable source of power
1
vote
0answers
113 views

In what environments can a dipolariton form?

In what environments can a dipolariton form? The article in Science in which it is introduced discusses it in the context of an optical cavity in a semiconductor. Can this quasiparticle occur ...
0
votes
1answer
700 views

Photons and phonons

A few months ago I asked about phonons. I got some very good answers but I still have difficulty getting an intuition for phonons, while somehow photons, which in many ways are similar and which I ...