Unanswered Questions
1,798 questions with no upvoted or accepted answers
14
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Do correlations in local quantum spin systems always decay exponentially or algebraically?
Consider translation-invariant quantum spin systems, that is qu-d-its on a lattice with a geometrically local Hamiltonian. Usually, such models are either gapped (in an ordered/disordered phase) or ...
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14
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Demystifying jamming in many-body systems
From a theoretical point of view, what has been the most successful approach to understanding jamming phenomena?
I understand there's still a lot of debate around this subject, namely whether a ...
- 5,601
12
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1
answer
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Hedin's equations and the ground state energy
Hedin's equations are an iterative scheme to calculate the Green's function $G$, the self-energy $\Sigma$, the vertex $\Gamma$, the polarizability $\chi$, and the screened interaction $W$.
However, ...
CommunityBot
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12
votes
1
answer
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What is the physical meaning of phase in a superconductor?
I am trying to understand the physical meaning of phase in the order parameter of a superconductor. In particular,I was looking at this article that states the phase $e^{i\theta}$ in the BCS ground ...
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11
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Research: Mott insulator and topological order
I'm an experimentalist who is mainly focusing on strongly correlated electron systems (SCES), in particular Metal-insulator (Mott) transitions in the classical example $V_2 O_3$. Recently I decided to ...
- 741
10
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1
answer
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Is there any heat loss in chiral edge channels of topological insulators?
If we are working with nontrivial topological insulator with broken time reversal symmetry then we can expect that we have some chiral edge states. Chiral states have the property that the current can ...
CommunityBot
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10
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Fourier transform of almost-periodic lattice?
For a perfectly periodic lattice of atoms, the density can be written as a Fourier series like any other periodic function. This Fourier representation is very useful, because it can be connected to ...
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301
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Thermalization at quantum critical point and quantum many-body scars
Quantum scar states are a hot topic in condensed matter physics. Quantum scars are the eigenstates of a many-body system (e.g. a spin chain) that weakly violate the eigenstate thermalization ...
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Failure of Hertz-Millis-Moriya theory for quantum phenomena
In the quantum critical phenomena of condensed matter, the earlier work by Hertz, Moriya and Millis develope the the Hertz-Millis-Moriya (HMM) theory of quantum phase transition.
Naively, they ...
CommunityBot
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Exact diagonalization by Bogoliubov transformation
I am developing a model of multiple gaps in a square lattice. I simplified the associated Hamiltonian to make it quadratic. In this approximation it is given by,
$$
H =
\begin{pmatrix}
\xi_\mathbf{k} &...
- 206k
9
votes
1
answer
977
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Do EM waves transmit spin polarization?
Suppose you have a normal dipole antennae (transmitter and receiver) . Spin polarized current (as opposed to normal current) is sent into the transmitter, it emits an EM wave and the Receiver receives ...
- 126k
8
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How does one measure effective mass in a multivalley semiconductor?
I understand the answer given in this question. It explains how we can measure the effective mass in a semiconductor.
However, I wonder what happens in the case of a multivalley semiconductor. Namely, ...
- 1,772
8
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3
answers
381
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Demonstration that electric current at equilibrium is zero in crystals
As it is well known, electrons at equilibrium (no external field) do not conduct electric current, i.e.
$\int_{BZ} dk\,v_{k}\,f(\epsilon_k)=0$
where $f(\epsilon_k)$ is the Fermi-Dirac distribution
$...
CommunityBot
- 1
8
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answers
257
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Is there a way to obtain an RG flow equation for Quantum spin systems using MERA
We restrict ourselves to ground states of translationally invariant 1d quantum systems.
I understand that there is the scale invariant MERA(multiscale entanglement renormalization ansatz) which ...
- 17.7k
8
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407
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Is that possible to derive Landau-Fermi liquid theory from microscopic equation?
This question arises from reading Wen's book "Quantum Field Theory of Many-body Systems (Oxford 2004)" p204
To appreciate the brilliance of Landau-Fermi liquid theory, let us look at the
many-...
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