4 votes
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How to test for possible negative mass of dark matter?

The paper you mention, Farnes 2018, provides an unconventional idea to explain both dark matter and dark energy. However, this idea has quickly been refuted, e.g. by Stepanian 2019 or by Socas-Navarro ...
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3 votes
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Why are Eigenvectors of a 1D quantum ising hamiltonian real

Why are Eigenvectors of a 1D quantum ising hamiltonian real Is the Hamiltonian real and symmetric? If so, then you can choose the eigenvectors to be real. Of course, since the eigenvectors are only ...
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3 votes

Is Bogoliubov transformation simply a basis transformation?

Any invertible transformation can be understood as a change of basis, but that doesn’t make it trivial (at least from a conceptual point of view). Some such transformations are so broadly useful and ...
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2 votes

Why electrons that form the cooper pairs only lie within $\omega_D$ of the Fermi energy in superconductors?

The maximum energy of the phonon interactions is $\hbar \omega_D$. Since the electrons are almost completely degenerate, only electrons within $\hbar \omega_D$ of the Fermi energy can then participate ...
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2 votes

Can we write the effective field theory for the toric code model?

No. Effective field theory only describes system near critical point. Toric code model is far from critical point. Thus "No". Toric code model realizes a $Z_2$-topological order. When a ...
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2 votes

"Universal" versus "nonuniversal" in the topological entanglement entropy

The idea is that $\gamma$ is constant throughout a phase - i.e., it can only change at a phase transition, i.e. when the gap closes. Thus, it can be used as a signature of the phase - in this sense, ...
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Can you magnetize iron by putting it in the air gap of a two parallel plates capacitor?

I think that you are referring to "the Maxwell term": the magnetic field that curls round a changing electric field. $$\nabla \times \mathbf B =\mu_0\epsilon_0 \frac{\partial \mathbf E}{\...
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2 votes
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What is the signal velocity in a very thin enameled magnet wire?

In theory, for a straight wire in empty space, the TEM mode centered on the wire has only finite energy in the insulation, but infinite energy outside. The insulation thus has no effect on the wave ...
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2 votes
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Fermionic Operator under time-reversal symmetry

This is essentially an issue of first quantization vs. second quantization. In second quantization we define the action of the time-reversal operator on the fermionic creation and annihilation ...
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1 vote

Anisotropic screening for charged particles in a magnetic field

I'm not an expert, but I think that there is no net effect, in part due to the Bohr-Van Leeuwen theorem. First of all, a static magnetic field does not influence the thermal charge fluctuations which ...
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1 vote
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Could you magnetize and at the same time elactrostatically charge a piece of rusted iron?

When we say "a piece of iron" it usualy ment a piece of steel. Pure iron is very uncommon. Many varieties of steel can be magnetized (they are feromagnetic). The rust on the surface does not ...
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1 vote
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How to harvest water passivley?

I think all the methods you list can be run using only the heat of the sun, and no other external power source. The general term for this type of water condenser is a solar still. If you search for &...
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1 vote
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How to use Density Functional Theory to get the correct energy spectrum

Solving the Khon-Sham equations yields the Khon-Sham orbitals $\psi_i$ and the KS orbital energies $\varepsilon_i$. The groundstate energy of the N-particle system is then obtained as $$ E = \sum_i^N\...
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Incredible electron drift velocity in atomic thin layer of graphene?

I would say that superconductivity and the high mobility of graphene are completely unrelated. From my understanding, the high mobility of graphene comes from two things. One is the intrinsic band ...
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What can cause charge density wave (CDW) in 3D metal except for fermi surface nesting?

There is a CDW in Chromium whose origin is still not completely understood. It may be driven by a spin-density-wave for which there is some nesting. See https://www.nature.com/articles/s41467-022-...
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Cooperative orders

The degrees of freedom in charge order and orbital order are exactly that; the charge and orbital degrees of freedom. For example, a charge density wave would be an example of charge order. For ...
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1 vote
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What is the difference between MOKE hysteresis loop and VSM Hysteresis loop?

MOKE is an optical technique that relies on the rotation of the polarization of light incident on a material with a nonzero magnetization. It is typically used for 2 dimensional materials. VSM is a ...
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1 vote

What's a charge density wave?

I think a better way to think about charge density wave is phenomenologically. Namely, it is a collectively ordered phase of the charge degrees of freedom that spontaneously breaks the translation ...
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Can the water remain in the vapor gas form at zero Kelvin (0K) temperature? (when the pressure is low enough or under other conditions)

According to the second phase diagram in Kelvin to near 0K, it seems the answer is no. Then I think you must be misreading the diagram, as I don't see any section where the vapor pressure is ...
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1 vote

Can the water remain in the vapor gas form at zero Kelvin (0K) temperature? (when the pressure is low enough or under other conditions)

If the pressure is very low, the molecules might be simply too far from each other to form bonds and reduce their energy via binding. This means, we will just have a bunch of molecules at large ...
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1 vote

Is Bogoliubov transformation simply a basis transformation?

"...it's just a simple basis transformation" — yes and no. Note that in the multi-particle case (what we are usually interested in) the Bogoliubov transformation is defined by its action on ...
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1 vote

Symmetry breaking in near free electron?

Translational symmetry is broken: instead of the invariance to arbitrary translations the system is no invariant only to the translations by a multiple of the lattice vector. In fact, what we have ...
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Questions regarding physical electronics

Not quite. Even in the discrete limit, you can solve the corresponding evolution using 2nd quantization, and you should get instep motion of Bloch oscillations (neglecting scattering). I don't ...
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1 vote

Composite fields and statistics

Disclaimer: I'm not a condensed matter theorist, and I find most statistical physics utterly impenetrable. However, this question also bothered me long enough to try to figure it out. Here's my ...
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