network profile
| bio | website | |
|---|---|---|
| location | Germany | |
| age | ||
| visits | member for | 8 months |
| seen | 2 days ago | |
| stats | profile views | 23 |
Graduate Student - Experimental Condensed Matter Physics
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Apr 26 |
comment |
Basic questions in Majorana fermions I always thought "Majorana fermions" are called fermions because they still obey fermion commutation relations and anticommute with other (CAR-algebra). They don't obey Fermi statistics though, which makes them "weird" fermions. |
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Apr 21 |
answered | Energy needed to lift and bring down an object |
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Apr 21 |
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How electricity, and generating electricity works on the atomic level? Please see britneyspears.ac/physics/dos/dos.htm for an example. They introduce the particle-wave duality and then calculate the density of states. I reckon you don't like the idea that a particle is a wave and vice versa? ; ) A wave has a wavevector $k$ and it also has a defined velocity just like a particle. And yes, if you conncet two wires, you will have a denser density of states in principle, but you have new spatial boundary conditions for your electrons. |
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Apr 21 |
comment |
How electricity, and generating electricity works on the atomic level? In principle you could track back every single energy band, they're just so close together that it's just not a feasible idea. Eventually you change from a sum to an integral and you integrate over momentum-space to get the density of states. This integral is indeed made up of small areas in k-space that have a length of $\frac{2\pi}{a}$ where $a$ is the lattice constant. And yes the electronic wave function (of the conduction electrons) spreads over the the entire 1kg crystal. The desriptions are "almost" equivalent, either little balls that move or a wave that is spread out. |
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Apr 21 |
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Effects of a very large magnetic field on the human body I'm not a chemist but how is a Van der Waals Bond related to a water molecule? The bond between $H$ and $O$ is polar covalent and the bond between $H_2O$ molecules is a $H$-bond. All of them should be harder to break than a simple dipole-dipole (van der Waals) interaction. |
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Apr 20 |
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How electricity, and generating electricity works on the atomic level? Hello AlanSE, why do you say these lines never existed? If you agree that let's say a hydrogen atom has sharp energy levels due to the Bohr-Sommerfeld quantization, then if you put two hydrogen atoms close to each other their wavefunctions will overlap and you end up with new sharp energy levels that define the new system (i.e. energy levels of a molecule). The same is even more amazing for $10^{23}$ of these atoms in a crystal and you will get bands in the continuum limit instead of single energy levels. E.g. quantum dots in a laser have these sharp energy levels due to confinement. |
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Apr 20 |
revised |
How electricity, and generating electricity works on the atomic level? added 177 characters in body |
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Apr 20 |
revised |
How electricity, and generating electricity works on the atomic level? added 177 characters in body |
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Apr 20 |
answered | How electricity, and generating electricity works on the atomic level? |
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Apr 20 |
comment |
Why does a superconductor obey particle-hole symmetry? Hello Luboš, could you elaborate why a semiconductor or a conductor can't have particle-hole symmetry but a conductor does? Why do you say that $E$ is not -> $2E_0 - E$? Also, what about excitons? They should come close to a Bogoliubov description. |
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Feb 8 |
awarded | Teacher |
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Feb 8 |
revised |
Confusion regarding photons? deleted 1 characters in body |
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Feb 8 |
answered | Confusion regarding photons? |
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Jan 19 |
accepted | What conductance is measured for the quantum spin Hall state when the Hall conductance vanishes? |
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Dec 19 |
asked | What conductance is measured for the quantum spin Hall state when the Hall conductance vanishes? |
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Dec 16 |
comment |
How is the topological $Z_2$ invariant related to the Chern number? (e.g. for a topological insulator) Thank you, this explanation did help! But I'm still trying to make an analogy to the Quantum Hall state where the Chern number was exactly equal to the number of one-way edge states (i.e. = winding number). How would you describe the relation of the "spin Chern number" to the number of edge states or the # of band crossings for a TI? I'm focusing on this picture because it would help me understand the topology (e.g. compare the "Seven bridges of Koenigsberg" from Euler".) |
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Dec 8 |
revised |
Why quantum mechanics? deleted 61 characters in body |
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Dec 8 |
answered | Why quantum mechanics? |
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Dec 5 |
awarded | Scholar |
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Dec 5 |
awarded | Supporter |
