The study of physical properties condensed phases of matter, including solids and liquids.
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Rice Allnatt distribution function
Can anyone give me an article of which explains Rice Allnatt distribution function or can you explain the function here?
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248 views
Analytic continuation of imaginary time Greens function in the time domain
Consider the imaginary time Greens function of a fermion field $\Psi(x,τ)$ at zero temperature
$$ G^τ = -\langle \theta(τ)\Psi(x,τ)\Psi^\dagger(0,0) - \theta(-τ)\Psi^\dagger(0,0)\Psi(x,τ) \rangle $$
...
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Why the peak of spectrum gets vague when the dimension is lower?
In a many-body system, we can know the spectrum function at a particular temperature from Green function. It means density of states. A peak of spectrum represents one mode. My question is that in the ...
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208 views
Does a quantum phase transition have latent heat?
As the title says, I am thinking about the question that whether a quantum phase transition has latent heat. If so, at 0 temperature, we can drive the system by some parameter from disorder phase to ...
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2answers
221 views
P-T Phase diagram. Density of material at critical point
One of the questions I had while reading through some material was:
Why is the density of a given volume of gas uniquely defined at the critical point, but not at the triple point?
Is it because at ...
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300 views
Kramer's-Kronig relations for the electron Self-Energy Σ
I'm currently studying an article by Maslov, in particular the first section about higher corrections to Fermi-liquid behavior of interacting electron systems. Unfortunately, I've hit a snag when ...
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1answer
94 views
Question about Classical Transport Theory
With a distribution function of the form $f=f_{0} + \vec{v} \cdot \vec{g}$, one can obtain the current density. My question is about $\vec{g}$; we assume a general solution to $\vec{g}$ of the form ...
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2answers
432 views
Why are Topological Superconductors hard to make?
Topological insulators (TI) have already been made in lab. Topological superconductors (TSC), being close cousins of TI, seem harder to make.
Why is that?
It seems that materials in connection with ...
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119 views
Notation in Spin Liquid
When construct spin liquid by projective symmetry group, we can classified spin liquids by the invariant group (IGG) of their mean field ansatze. For example, we can have Z2, U(1) and SU(2) spin ...
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456 views
Effective Mass and Fermi Velocity of Electrons in Graphene:
In graphene, we have (in the low energy limit) the linear energy-momentum dispersion relation: $E=\hbar v_{\rm{F}}|k|$. This expression arises from a tight-binding model, in fact $E =\frac{3\hbar ...
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291 views
Identifying a critical phenomena?
I have a system with a number of measurables (in time). Some measurables are discrete some are continuous (within the measurement accuracy). How can I determine whether my system experiences ...
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1answer
128 views
Band Structure and Carrier Recombination/Generation
So i've been a bit confused, looking at PN junction, semiconductors and the like (trying to nail down how exactly semiconductors work, transistors and such). I've read the wiki on band structure ...
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262 views
Wave functions for three identical fermions
I would like to express the wave functions for three identical particles, each with orbital angular momentum $L=1$ and spin angular momentum $S=1/2$, in terms of single-particle wave functions. In ...
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218 views
Matrix element in quantum mechanics
This is about a matrix element of a second quantized operator.
Consider the operator
$$
U=\sum_{\alpha\beta}U_{\alpha\beta}c^{+}_{\alpha}c_{\beta}
$$
Something strange emerges if we calculate again ...
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1answer
304 views
What conductance is measured for the quantum spin Hall state when the Hall conductance vanishes?
It's probably just a definition, but what did König et al. actually measure when he confirmed
the existence of surface states in CdTe/HgTe/CdTe quantum wells (see http://arxiv.org/abs/0710.0582)?
...
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24 views
What is a Palais-Smale sequence?
I was studying a paper on existence of discrete breathers by F. Gazzola and he uses the properties of Palais-Smale sequences to do many things that i dont understand,
my questions are
...
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1answer
141 views
Energy spectrum of a tight-binding model
Consider the one-dimensional tight-binding Hamiltonian
$$\mathcal{H}=t\sum_m\left(a^\dagger_m a_{m+1}+a^\dagger_{m+1} a_{m}\right).$$
With the lattice constant set to 1, the energy spectrum is given ...
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318 views
What is the experimental status of AdS/CFT, AdS/QCD, AdS/CMT, etc?
What experiments have challenged or supported AdS/QCD, AdS/CMT, etc? What experiments should we look forward to do this?
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84 views
why is orbital moment quenched while atoms forming solid
atom has well defined spin(up and down) and orbital(s,p,d,etc) momentum, but when forming crystals, why the spin degree continues to be good quantum number while orbital momentum is quenched?
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130 views
Literature on fractal properties of quasicrystals
At the seminar where the talk was about quasicrystals, I mentioned that some results on their properties remind the fractals. The person who gave the talk was not too fluent in a rigor mathematics ...
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Will Anderson's Poor Man's Scaling loose its effect when band width is small?
The s-d interaction Hamiltonian is as fellows
$H_I=Js.S$, J is the coupling strength.
We focus on the antiferromagnetic case, where $J>0$.
According Anderson's poor man's scaling, the ...
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1answer
295 views
Physical meaning of magnetic length
What is the physical meaning of magnetic length $\ell_B=\frac{\hbar c}{e B}$ in 2D electron system under magnetic field? When $\ell_B \longrightarrow a$, where $a$ is the lattice constant, does that ...
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613 views
How much can AdS/CMT tell us?
I will begin my research on AdS/CMT, however I find AdS/CMT is only a phenomelogical method, so I want to know can AdS/CMT give some results the condensed matter physicists can not give, or even ...
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54 views
What is Resonance Width? Why we use it to distinguish different Regimes of the Anderson Model
The single inpurity Anderson Hamiltonian is
...
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2answers
113 views
Why is a critical system equal to a gapless system?
In condensed matter physics, people often say that a system without energy gap is a critical system. What does it mean?
Any help is appreciated!
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72 views
Phonon-polariton literature resources? [closed]
What is a good resource for studying phonon-polaritons?
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Canonical averages in a Fermi gas aka generalized Fermi-Dirac distribution
I am in the process of applying Beenakker's tunneling master equation theory of quantum dots (with some generalizations) to some problems of non-adiabatic charge pumping. As a part of this work I ...
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194 views
Intuitive description of what a “Fermi Gas” really is?
This question is based in the area of material equations of state. I am wanting to know what a Fermi Gas really is. I have searched in several places for a decent description, but I have not found ...
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56 views
Is there real materials have Lieb lattice structure? [closed]
Is there real materials have Lieb lattice structure?
Some examples?
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207 views
Simulating the evolution of a wavepacket through a crystal lattice
I am interested simulating the evolution of an electronic wave packet through a crystal lattice which does not exhibit perfect translational symmetry. Specifically, in the Hamiltonian below, the ...
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43 views
the poles of impurity system's Green's function
Denote the pure system as system 1, with both continuum and discrete eigen energy. $G_0$ is its Green's function.
After introducing some impurities, we call the resultant system system 2 with new ...
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774 views
How Fundamental is Spin-Orbit Coupling to Topological Insulators?
I'm well aware this is a very active area of research so the best answer one can give to this question may be incomplete.
Topological states in condensed matter are well-known, even if not always ...
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1answer
50 views
Limitations in using FLEX as a DMFT solver
When using the fluctuating exchange approximation (FLEX) as a dynamical mean field theory (DMFT) solver, Kotliar, et al. (p. 898) suggest that it is only reliable for when the interaction strength, ...
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158 views
Thermodynamic limit “vs” the method of steepest descent
Let me use this lecture note as the reference.
I would like to know how in the above the expression (14) was obtained from expression (12).
In some sense it makes intuitive sense but I would ...
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81 views
guage invariance in Laughlin's argument
In Laughlin's gedanken experiment which aims to explain quantization of Hall conductance, one takes the adiabatic derivative of the Hamiltonian with respect to vector potential. Now it seems that it ...
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1answer
102 views
Measurement of topological spin
How do you measure the topological spin of an anyon? So how could an experimental setup look like? Is topological spin an observable at all?
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Good reading on the Keldysh formalism
I'd like some suggestions for good reading materials on the Keldysh formalism in a condmat context. I'm familiar with the imaginary time, coherent state, path integral formalism, but lately I've been ...
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Lagrangian for Goldstone mode + topological excitation
The XY-model Hamiltonian is the following,
$${\cal H}~=~-J\sum_{\langle i,j\rangle} \cos (\theta_i -\theta_j).$$
The Goldstone mode corresponds to term $(\nabla \theta)^2$ in the effective ...
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1answer
113 views
What is nonlocal resistance?
We are first taught to calculate local resistance, where current and voltage are on the same part of the material.
But many experiments measure nonlocal resistance, where current and voltage are ...
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2answers
286 views
Has Bose-Einstein theory been considered for dark matter?
Has Bose-Einstein theory been considered for dark matter?
The theory would explain why no measurable radiation is emitted due to zero temperature--its lack of interaction with other matter and its ...
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55 views
Two-fluid description of superfluidity
I'm trying to teach myself about superfluidity and I'm slightly confused on the ''two-fluid'' description. From what I understand, the superfluid is considered to be a mixture of two fluids, a ...
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109 views
String-net condensation in 3D
In 2D and 3D quibit models, string-net condensation can happen. In 3D or higher models, is it possible for surfaces (instead of just strings) to condense?
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Renormalization Group for non-equilibrium
For equilibrium/ground state systems, a (Wilson) renormalization group transformation
produces a series of systems (flow of Hamiltonians/couplings $H_{\Lambda}$ where $\Lambda$ is the cut-off) such ...
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249 views
optical equivalent of a superconductor
Is there some material state that can propagate light indefinitely without dissipation or absorption, like superconductors are able to trasmit current indefinitely?
If not, then the question is, why ...
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1answer
180 views
What is different between resolvent and green function
I bumped into a book, where Resolvent $R^{\pm}(E)$ is defined as
$e^{\mp iHt/\hbar}=\pm\frac{i}{2\pi}\int_{-\infty}^{\infty}dER^{\pm}(E)e^{\mp iEt/\hbar}$
and
$R^{\pm}(E)=\frac{1}{\pm ...
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1answer
120 views
Is the liquid/solid line infinite?
Starting from the triple point, is the melting line between solid-phase and liquid-phase infinite? If not, why does it end? Because pressures are so high that classical inter-molecular interactions ...
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2answers
188 views
Boundary conditions for crystals
As students on solid state physics, we are all taught to use the periodic boundary condition, taking 1D as an example:
$\psi(x)=\psi(x+L)$
where $L$ is the length of the 1D crystal.
My question is:
...
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1answer
152 views
What is replica symmetry breaking, and what is a good resource for learning it?
M. Mezard, G. Parisi and coworkers have written about replica symmetry and its breaking in spin glasses, structural glasses, and hard computational problems.
I am just getting acquainted with this ...
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160 views
Meissner Effect for Type-II Superconductors
I was wondering whether the breakdown field strength for the Meissner effect may be attributed to the Zeeman effect? I can see the latter (along with the Stark effect) to be more analogous to electron ...
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220 views
Why do phonons cause excellent heat conduction in diamonds?
Phonons are the quantum of lattice vibrations in crystals and are not to be confused with photons, the gauge bosons of the electromagnetic force. Apparently, they contribute to heat conduction, but I ...
