Superconductivity is the transmission of current with no resistive losses, and is one of the most active areas of condensed matter physics research.

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Is there contradiction between BCS state and the Superselection rule? [closed]

BCS state can be projected into particle number basis. There are different particle numbers in different wave component. But according to the superselection rule there seems to be no such state. I am ...
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How to get the expectation value of the spin of a generate spin triplet states? [closed]

For two spin-1/2 electrons, the general spin triplet states is a linear combination of the three basis states: $\left.|\uparrow\uparrow\right>, ...
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Lorentz force on superconductors?

If current flows on the surface of a superconductor(for both type I & II) and is exposed to an exterior magnetic field, will a superconductor experience a Lorentz force? Knowing that a ...
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Spin interaction of Virtual Phonon's forming Cooper Pairs

Im confused about the spin of virtual Phonons, my lecture notes suggested that even spin bosons repel opposite charges, and it also suggested that cooper pairs form by considering the "Charge" to be ...
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Lorentz force on type II superconductors?

The electrical resistance being zero in a superconductor, if a magnetic field is strong enough to generate vortices where the flux lines will pass through the material, and the current flow is ...
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52 views

AdS/CFT and Kondo problem/ Ginzburg-Landau theory

I was reading the review on Unconventional superconductivity by Mike Norman, towards the end (page 22) he comments two things about AdS/CMT: "In the condensed matter context in two dimensions, one ...
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Is there a database or a classification of High-temperature superconductors?

I was wondering if there exists a list with all (or most of) the High-$T_c$ superconductor materials. In particular I'd like to know if there are databases or review that classifies them by their ...
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1D superconductivity does not exist even at zero temperature?

In class Professor claimed that 1D superconductivity does not exist even at zero temperature. I did a preliminary search and found papers on 1D superconductors. Did I or the Prof make a mistake or ...
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Do we always have particle-hole symmetry?

If we write the BdG equation for any model, and double the degrees of freedom (e.g. 4N*4N matrix for a N site chain), then we are guaranteed the particle-hole symmetry. Is there any constraints to do ...
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What's the difference between charge density wave and charge ordering for superconductors

So far, my understanding is that they are the same. Charge ordering is a phase transition and the material will have charge density waves once it's in a charge ordered state...? This sounds too simple ...
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Majorana fermions in s wave superconductor

I need some help to understand the majorana fermions in $s-$ wave superconductor and to check whether following method is correct For $s-$ wave superconductor we can write the Hamiltonian as ...
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Usage of rare earth barium copper oxide (ReBCo) superconductors (for fusion reactors)

Recently, scientist from MIT have proposed a new design for a compact fusion reactor, see for example this ArXiV paper. I do not want to discuss the physics of their reactor but am more interested in ...
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Difference between a Hamiltonian and its mean-field form?

In most solid state physics text books, BCS theory is introduced in the following way: The authors introduce a mean-field parameter (based on the superconduncting pair) and upon that, they reduce the ...
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Three-dimensional flat bands and how to create them?

Consider a three-dimensional non-interacting system with translational invariance. It is easy to create a two-dimensional flat band by putting this system into a uniform magnetic field. The energy ...
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Can the hole concentration of cuprate superconductors generally be determined from lattice parameters?

As it is known, in YBCO superconductors, lattice parameters are strongly dependent on hole concentration, so hole concentration can be determined by measuring the c-axis parameter, see e.g. "Oxygen ...
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58 views

Cooper Pair Breaking and Quasiparticle Excitations

My question concerns the breaking of Cooper pairs and the excitation of quasiparticles. At T = 0 all electrons are condensed in the ground state as cooper pairs. If one increases the temperature one ...
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Superconductivity and time-reversal symmetry

Let us consider a system of a 1D edge of a 2D topological insulator in proximity to an s-wave superconductor. The system is described by the Hamiltonian: $$ H =\frac{1}{2} \int \mathrm{d}x \ ...
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Effect of doping in Superconductor

Doping an element (for example element substitution) could be lower down the critical temperature of superconductor, but i don't know the mechanism behind this, is it because more bosons need to ...
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What is crystal “supermodulation”?

I am researching the pair density wave in cuprates, and during my reading I came across a term "crystal supermodulation". I believe it relates to BSCCO. Can anyone give me a definition or give me a ...
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80 views

Criticality in BCS Theory

Can someone provide me with a pedagogical introduction into the role of criticality in BCS theory? The QCD condensate is due to strong coupling. The BCS condensation involves only weak coupling - ...
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61 views

Why superconductor have vortex

Sorry guys I really don't understand the idea of vortex in superconductor, why superconductors type II have vortices ? Thanks in advance!
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Tunnelling from a normal metal into a superconductor

a similar question has already been asked in the forum but unfortunately I cannot yet comment and still think that some things left unanswered. My question is in general concerning the tunnelling ...
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190 views

Particle-Hole transformation in Superconductor

The Bogoliubov - de Gennes equation has a emergent particle-hole symmetry: $$ \mathcal{P}H\mathcal{P}^{\dagger} = -H\text{.} $$ My question is now what happen to the Nambu spinor: $$ ...
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Quasiparticle poisoning in fractional Josephson effect

It is predicted that in the presence of Majorana zero modes, which can mediate a current that is effectively carried by half of a Cooper pair, a Josephson junction can exhibit a periodicity of 4$\pi$. ...
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I need textbooks or articles connected to interplay between superconducting and magnetic layers in thin film heterostructures

I need textbooks or articles connected to interplay between superconducting and magnetic layers in thin film heterostructures. Links would be appreciated though names of articles and textbooks or ...
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51 views

Josephson junction exceeding the coherence length of the cooper pair

In this recent paper http://arxiv.org/abs/1504.03286, the authors present the data that they measured Fraunhofer-like diffraction pattern in a Josephson junction with graphene sandwiched between ...
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Exact Diagonalization of a BdG Hamiltonian on a Finite Lattice

I would like to numerically find the edge modes of a $p_x$ + $i p_y$ BdG Hamiltonian. The lattice version is given by H = $\sum\left[-t \left(c_{m+1,n}^{\dagger} c_{m,n} + \text{h.c} \right) - ...
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How feasible is a hoverboard arena using superconductors? [closed]

How feasible would it be to make a hoverboard arena, by analogy with skateboard arena, by having a strongly magnetic floor and a superconducting hoverboard, or vice versa? I don't know the equations ...
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Are there any practical applications of Mott insulators and Superfluids?

The potential applications of Bose-Einstein condensated is discussed here, I was wondering whether anyone could produce a similar argument for Superfluids and Mott insulators. EDIT: I fully realise ...
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BCS/Cooper Pairing in Electrons during Superconducting

Why do electrons with negative charges pair together during superconducting? Since electrons have negative charges, shouldn't they repel each other instead of pairing up? As far as I understand, ...
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Should a superconductor act as a perfect mirror?

I have been told that metals are good reflectors because they are good conductors. Since Electric fields in conductors cause the electrons to move until they cancel out the field, there really can't ...
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Quantum levitation - Real Load Weight

Can you please try to tell if it's real to create a device based on Quantum levitation that can hold adult person a few centimeters above ground. I'm curios because everywhere we see the super ...
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About superconductivity

If I take a magnet and a superconductor than it will expel the magnetic field lines of the magnet. now if there is a coil of wire on the other side of the superconductor and i start to warm up the ...
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How are superconducting magnets powered?

Since the resistance of a superconducting circuit is exactly 0, it would try to draw infinite current from a power source, since P=I^2*R. For a finite power source, I-> infinity as R->0. Correct? ...
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Why is there a superconducting dome in superconductors?

Generally speaking, by the well-known BCS theory, the more carrier density( density of state at Fermi surface) leads to higher critical temperature. However, in many researches, people fond that the ...
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Formation of vortices in superconductors

So I'm trying to understand how mixed state of a type II superconductor becomes the energetically favourable state. I've been through a simple approximate calculation considering a S-N boundary to ...
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Are quantum computers at least build able?

Assuming a highly unrealistic where you basically have unlimited money to burn. Is it possible to a build a size scalable quantum computer? My premise is that I often read tha people have a made a ...
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Eddy current brake with superconductor

There are eddy current brakes used with metal plates to stop trains. It converts kinetic energy of the metal plate to heat via eddy current on it. So what if we have a superconducting metal plate and ...
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Shorting a Superconducting Coil with A/C

When a superconducting coil carrying a direct current is shorted, it continues to carry the current without loss (approximately), assuming it stays cooled and superconducting. What would happen if ...
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Procedure for wrapping a superconducting coil around a cylindrical shell?

I don't know if experimental physics questions are allowed on this site - please direct me to the proper SE if it doesn't belong here. I need to wrap a few layers of superconducting wire (~80 ...
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Number Conserving Superconductors

Usual BCS theory used to describe superconductors violates particle number conservation, this is allowed since that theory is written in a grand canonical ensemble (i.e particles can be exchanges ...
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Superconductivity and superfluidity energy dissipation

All articles say that in superconductive state, the materials have exactly zero resistance, but is this the case in real life experiment?, because if this were true, a process without energy ...
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Bogoliubov de Gennes Hamiltonian, Expansion of electron operator

Suppose we are given a particle-hole symmetric Hamiltonian H. This type of Hamiltonian is usually diagonalized by a Bogoliubov transformation. In this context in the literature the local electron ...
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Synthesis of Fe-based superconductors

Polycrystal cuprate superconductors are generally prepared by solid state reactions: Starting reagents are in powder form, they are mixed to each other and placed into furnace on high temperature ...
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Is the current density ${\bf j}$ an observable?

The current density ${\bf j}$ is most easily defined from$$ I = \int_{\text{cross-section} \atop \text{of wire}} \textbf{j}\cdot d\textbf{S}, $$ where $I$ is the current flowing through the wire. From ...
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Eigenvector distributions, random matrix theory and the ten-fold way

For various applications the distribution of components of the eigenvectors of random matrices is of interest. For example, in the case of a matrix in the Gaussian orthogonal ensemble this ...
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Why does a magnet rise up from the surface of a superconductor after the superconductor reaches critical temperature?

From my current understanding, when a magnet is placed above a superconductor below Tc, it hovers due to the Miessner Effect (total exclusion of magnetic fields from within the superconductor) due to ...
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superconducting coherence length explanation

What is the formula for superconducting pair coherence length in real space? How is it calculated in a two-dimensional square lattice? I found this formula below: $$\zeta = \frac{\sum_{\bf{r}}r^2 ...
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Wavefunction for Anti-Pfaffian state

What is the most general form of a wavefunction for anti-Pfaffian in variables $\{z_i\}$ which represent the positions of electrons on a two dimensional plane?
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Flywheel energy storage: Why not use room temperature diamagnets instead of superconductors?

Flywheel energy storage has garnered some interest from academia and industry for its potential to store surplus electrical energy efficiently in kinetic form. Modern designs use magnetic bearings ...