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3
votes
2answers
168 views

Spin drift velocity?

I am currently reading this Phys Rev paper by H C Torrey. In this paper, he derives the Bloch equations with an additional diffusion term. He says that the current density is given by $$\mathbf ...
1
vote
1answer
285 views

Bose–Einstein statistics exercise

I've a basic Bose–Einstein statistics exercise. I've tried to solve it in two ways, but each way gives a different result. We have $n$ identical bosons without interactions at temperature $T$. There ...
0
votes
1answer
68 views

Quantum Dimer Model (QDM) hamiltonian

The Hamiltonian given by Rokhsar-Kivelson QDM is based on tensor products of the state vectors. Why is this the case?, is it because the lattice model is a mixed state? It'd be great if someone could ...
0
votes
1answer
61 views

Does spin degeneracy affect ideal Fermi gases in any way as T->Infinity?

In other words, given any system comprised of an ideal Fermi gas, in the high-temperature (classical) limit, are there any observable thermodynamic quantities (pressure, volume, energy, density, etc.) ...
10
votes
0answers
187 views

Anyons as particles?

I'm trying to understand the basics of anyons physics. I understand there is neither a Fock space they live in (because Fock is just the space of (anti-)symmetrized tensor product state, see e.g. ...
7
votes
0answers
357 views

Is the “particle number” of “electrons” well defined in Wen's string-net theory of elementary particles?

According to professor Wen's string-net theory, electrons can be viewed as the elementary excitations of string-net objects. Just like the phonons and magnons are the elementary excitations of ...
2
votes
0answers
37 views

dependence of braiding matrix element on the fusion product of anyons

In the case of Majorana fermions (MFs), one knows that if one braids MF $a$ with MF $b$, then braiding matrix element $R^{c}_{ab}$ depends on the state $c$ which is the fusion outcome of $a$ and $b$. ...
2
votes
0answers
47 views

Bose-Einstein-statistics out of fermionic many body system

ok, let me try this again. How do I get to atoms obeying Bose Einstein statistics from considering the fermionic many body problem of a bunch of electrons, protons and neutrons forming these ...
1
vote
0answers
20 views

What fugacity actually is and how it's plays an important role on Bose gas?

We know that the average occupation number cannot be negative for all systems and chemical potential must be negative in Ideal Bose Gas. This fact leads us to arrive a conclusion for fugacity which is ...
1
vote
0answers
21 views

What are the instances of usage of four color theorem in the theory of fractional statistics?

How important is four-color theorem (Hypothesis) in theory of Fractional Statistics?
1
vote
0answers
31 views

The symmetry normalization factor of wave functions in quantum statitics

Now I am studying statistical mechanics by R.K.Pathria & Paul D.Beale's Statistical Mechanics(3rd Edition). In page 134, the book claims that the wave function $\psi$ of a system composed of N ...
1
vote
0answers
60 views

Exploiting Resonance to Make a Bound State with Gamma Rays (and other Very High Energy Particles)

One obvious consequence of any finite potential is that a high enough energy wave-function will not form a bound state, either they are high enough energy they will generally just bypass the barrier ...
1
vote
0answers
61 views

grand-canonical ensemble

I was wondering if the following reasoning is correct for example for electrons in the classical or qm grand-canonical ensemble? Is it always valid in the grandcanonical ensemble to calculate the ...
1
vote
0answers
119 views

Chemical potential related with quantum and classical limit in ideal gas

For ideal gas we have chemical potential $\mu = \tau \ln \left(\frac{n}{n_Q}\right) $ where $n = N/V$ number density and $n_Q = \left(\frac{M\tau}{2\pi \hbar^2}\right)^{\frac{3}{2}} $ Note we call ...
1
vote
0answers
90 views

Diamagnetism of a degenerate electron gas for weak fields

In the book "Statistical Physics, Part I ($3^{{\rm rd}}$ edition)" by Landau and Lifshitz, at $\S59$ when he treats the diamagnetic part of the magnetisation of a degenerate electron gas for weak ...
1
vote
0answers
114 views

Is there a systematic way to determine the relevant variables needed to describe a nonequilibrium system?

In strong nonequilirium, the statistical operator describing the system depends on an infinite number of variables (BBGKY-hierarchy), contains information about all the previous states starting from ...
0
votes
0answers
22 views

Fugacity in Bose-Einstein condensate

Just a simple question, I didn't manage to find out in my books... The fugacity $z = e^{\beta \mu}$ in the case we have condensation in a bose statistics. Is it always 1 or $z \to 1$? In the ...
0
votes
0answers
30 views

Fermion gas exercise with annihilation and creation operator

The number states in the ground state of fermion gas are, \begin{align} n_l &= 1, \qquad \epsilon_l < \epsilon_F \quad (\epsilon_{F} \text{ is the Fermi energy.}) \\ n_l &= 0 \qquad ...
0
votes
0answers
28 views

Pauli Master Equation usable for Bose-Einstein condensation?

As I am not an expert in the field, please correct me accordingly. Now to my problem: I wondered whether it is justified to use the Pauli Master Equation (i.e. linear coupling to markovian ...
0
votes
0answers
69 views

Thermal fluctuations in metals

My professor said that the $k_BT$ displacement in the energy levels of the band electrons is due to the space-thermal displacement of the potential of the ion host. I think that this displacement is ...
0
votes
0answers
151 views

relative phase/sign in $\Psi$ after exchange of composite particles with angular momenta

I'm reading Quantum Liquids by A.J. Leggett and became confused by the following statement in the first chapter. Consider now a pair of such identical atoms. In the absence of appreciable coupling ...