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What is the relation between linear elastic theory and phonon transport?

Clearly there should be a limit where both are one and the same, isn't it? I think the underlying contrast you want to make is the continuum model of a solid vs the atomistic model of a solid. The ...
lnmaurer's user avatar
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Why is an FCC lattice the reciprocal lattice of a BCC Lattice?

It might be due to symmetry, a high symmetry system may keep it's periodic structure even when passing from the starting lattice to its dual lattice, for example considering two dimensional lattices ...
EL.K. MORAD's user avatar
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Why is an FCC lattice the reciprocal lattice of a BCC Lattice?

Each primitive vector of the reciprocal basis must be orthogonal to $2$ of the primitive vectors of the lattice basis. And the dot product to the other must be $2\pi$. The primitive vectors of the FCC ...
Claudio Saspinski's user avatar
2 votes

Why is an FCC lattice the reciprocal lattice of a BCC Lattice?

I'm not sure if this is the sort of answer that you had in mind, but it might help somewhat. A generic, not-necessarily-cubic crystal with a body-centered symmetry has sixteen generators of ...
TLDR's user avatar
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0 votes
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Line integral in Peierls substitution

In the tight-binding method, the finite difference approximation $\psi'(x) \approx \frac{\psi(x+a/2) - \psi(x-a/2)}{a}$ is made, which means that the momentum operator can be approximated in the ...
Bio's user avatar
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Free acoustic phonon propagator

The reason why you get a weird pole at $\omega = 0$ in your first attempt to find the propagator of a free acoustic phonon is that the transversal oscillations which are always part of the ...
Gheorghita Victor-Basarab's user avatar
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How to understand the concept of a fluxon, the dual of the Cooper pair?

Yes, it is a magnetic flux quantum, but technically you are only supposed to call it a fluxon when it is actually a flux soliton, meaning a soliton solution to the sine-Gordon equation in a long ...
Michael Frank's user avatar
-1 votes

Why only the phonon with $k=0$ contribute Raman intensity?

In deficit k cohesion or adhesive or covalent bond structure non-chemically but harmonically through electronic microscopic or oscillation dissertive spacing analysis and readings should get you the ...
Demarco Martin's user avatar
1 vote
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Delocalized electrons in the Hubbard model for Mott insulators

'The Hubbard model is an approximate model used to describe the transition between conducting and insulating systems.' (Wikipedia) It does so by considering two parameters, the hopping term t and the ...
my2cts's user avatar
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Algorithm to check difference in qubit states in terms of qubits numbers

Your example assumes that all four qubits have been measured, so each one is in an eigenstate - either $|0\rangle$ or $|1\rangle$. As has been pointed out in a comment, once you have measured all four ...
gandalf61's user avatar
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Problems about "boundary conditions and topology"

For question 1, the point is that closed wilson loops form gauge-invariant objects that cannot be gauged to be trivial. In periodic boundary conditions (e.g. for the square lattice on a torus), the ...
QCD_IS_GOOD's user avatar
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1 vote
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Why acoustic phonon dispersion cross $\omega=0$ at $k=0$?

For the acoustic mode, $k=0$ means all lattice points oscillate in phase. But still, they are oscillating so each lattice point must have some finite frequency (otherwise they would hold still or ...
hft's user avatar
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Are photons inside the media massive? If yes, why there is no Meissner effect?

The quantum equation in the middle of the above page is related to the quantum telegraph equation recently derived by Arbab that reads (https://doi.org/10.1016/j.ijleo.2017.05.002) $$\frac{1}{c^2}\...
Maxwell's user avatar
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2 votes
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Can the hybridization of edge states in the 1D SSH model be observed numerically?

To answer point 1, you should look at the eigenvalues for those two modes: They should be very close, but not the same. This might very likely also answer 2 -- the hybridization should go down ...
Norbert Schuch's user avatar
1 vote

What is the meaning of screened potential?

You are right in saying that the Coulomb potential includes the interaction between every particle in the system. However, screened potentials are not intended as another potential. They efficiently ...
GiorgioP-DoomsdayClockIsAt-90's user avatar
0 votes

What is the meaning of screened potential?

why do we need another potential besides the Coulomb one that includes the interaction between every particle in the system? The problem is that we can not solve the problem if we include all the ...
hft's user avatar
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7 votes

Since anyons cannot exist in our 3+1D world, what does it mean to have discovered them? Why should we study them?

The short answer is that no, you will in principle never run into issues describing your system with only fermions and bosons, as physical reality indeed only consists of these two particles. Whether ...
Codename 47's user avatar
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3 votes

Is there a blackbody spectrum of photons inside a solid?

In thermal equilibrium there are definitely photons inside a solid. They're bosons, so they will be described by the Bose-Einstein distribution. But they won't necessarily have a "blackbody ...
knzhou's user avatar
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1 vote

Why the symmetry is not $Pin(1,3)$ or $Pin(3,1)$ in condensed matter physics?

Here is the answer from myself. The group $Pin(1,3)$ has group elements time reversal $T$ and reflection $M_i$ along 3 spatial axes such that $T^2=1$, $M_i^2=-1$ and $TM_i=-M_iT$, $i=x,y,z$. Similarly,...
edittide's user avatar
1 vote

Why aren't completely random quantum states 'physical'?

The statement "Completely random states are generically not physical" only makes sense in a very specific context. An obvious counter example being the totally mixed state $\rho=I/d$ being &...
Jun_Gitef17's user avatar
1 vote
Accepted

Sublattice Magnetization of Heisenberg Model on triangular lattice

Why does no SSB in finite systems imply we have to look at $\hat m_z^2$ instead of $\hat m_z$? This is a common point to get confused about SSB. To really understand it, you would actually need to ...
Jun_Gitef17's user avatar
1 vote

What is parity of charge?

Charge parity conservation means that charge is conserved modulo 2. This is because of the $\mathbb{Z}_2$ nature of the symmetry (as opposed to usual $U(1)$). Another way to see this is that by ...
Nandagopal Manoj's user avatar
1 vote

Understanding the left-canonical matrix product state

Let us work through your example, i.e., $2^6$-dimensional normalized complex vector $|\psi\rangle$ \begin{equation} |\psi\rangle=\sum_{\sigma_1,\sigma_2,\ldots,\sigma_6}\psi_{\sigma_1,\sigma_2,\ldots,\...
Adam's user avatar
  • 31
1 vote

How the $-2t\cos(k)$ term appears in the dispersion of the $1D$ tight binding model?

I guess it won't be important anymore but I still would like to clarify: I guess you are refering to the beginning of page 6. The step you are confused of is not using the commutator relations of ...
ChrisG's user avatar
  • 11
1 vote

What is topological about topologically ordered states?

Topological order, by definition, describe the internal order of gapped liquid state of a lattice model that does not have any symmetry (0-form, higher-form, or non-invertible). More precisely, two ...
Xiao-Gang Wen's user avatar
0 votes
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Heisenberg Hamiltonian in terms of spinon operators

I think you probably haven't fully taken into account the anticommutation relation $ \{ f_{i\alpha}, f_{j\beta}^\dagger\} = \delta_{ij} \delta_{\alpha\beta}$. After applying the Pauli matrix relation ...
Anyon's user avatar
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0 votes

Thermal ground state?

To get the ground state expectations you need to set $\beta\to \infty$ (zero temperature). You can read off the spectrum by focussing on just two opertors $\psi(p, t_1)$ and $\psi(p,t_2)$ and looking ...
mike stone's user avatar
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1 vote

$\mathbf k\cdot\mathbf p$ Hamiltonian

I am not sure what $P_{cv}(k)$ and $C(s)$ are without some more context, but we can work through the $k\cdot p$ model from the beginning and continue the dialogue if you're still unsure. $k\cdot p$ ...
intraband's user avatar

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