A flow with no viscosity
Superfluidity refers to a flow with no viscous dissipation. It is an ideal inviscid flow mathematically described by the Euler's momentum equation.
Questions tagged [superfluidity]
259 questions
54
votes
5 answers
Will a propeller work in a superfluid?
Will a propeller work in a superfluid? Opinions differ.
JDługosz
- 5,357
24
votes
1 answer
What is so topological about topological phase transitions?
I am studying the KT-transition, which is called a topological phase transition. The phase transition is driven by vortices in a 2-D superfluid, where it is shown that at a critical temperature $T_c$ free vortices are energetically favoured over…
B. Brekke
- 1,842
23
votes
4 answers
What observables are indicative of BCS Cooper pair condensation?
What observables are indicative of BCS Cooper pair condensation?
"Thought" experiments and "numerical" experiments are allowed.
This question is motivated by the question Has BCS Cooper pair condensate been observed in experiment? ,
and by our…
Xiao-Gang Wen
- 13,725
19
votes
2 answers
How to understand the emergent special relativity in the superfluid?
The superfluid vacuum theory was proposed to understand some features of the vacuum (aether) from the emergence point of view. Although made up of non-relativistic atoms, the low-energy excitations of superfluid, i.e. the phonons, are said to be…
Everett You
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- 44
- 74
18
votes
2 answers
Are there Goldstone bosons in 1D or 2D?
The Mermin-Wagner theorem states that
continuous symmetries cannot be spontaneously broken at finite temperature in systems with short-range interactions in dimensions d ≤ 2.
And Goldstone bosons are
new excitations that appear when there are…
João Bravo
- 794
18
votes
2 answers
Why are superfluid vortex lattices stable?
Both (a) neutral superfluids that are externally rotated, and (b) type-II superconductors (i.e. charged superfluids) under applied magnetic fields between the critical fields $h_{c1}$ and $h_{c2}$, have topological-defect vortex excitations (which…
tparker
- 51,104
15
votes
1 answer
What is off-diagonal long range order in superfluid?
From Wikipedia:
[...]Off-diagonal long-range order (ODLRO) [...] exists whenever there is a macroscopically large factored component (eigenvalue) in a reduced density matrix of any order.
How to understand the ODLRO in superfluidity?
Timothy
- 2,539
15
votes
3 answers
Would an airplane flying through superfluid helium experience lift and drag?
Would an airplane flying through superfluid helium experience lift and drag? The airplane is presumed cold enough to not heat up the helium.
yippy_yay
- 2,648
14
votes
1 answer
What is the difference between superfluidity and Bose condensation?
My question is about zero-temperature ground state of a Bose system. Suppose that the system stabilizes a BEC order parameter, say $\langle b^+ \rangle$, and fixes its phase. Is this a superfluid? And vice versa. In 2D Bose-Hubbard model one…
danport
- 173
14
votes
1 answer
Feshbach resonance in simple terms
I was reading up Feshbach resonances in cold atoms and I was unable to grasp the concept. I will tell you what I have understood. We consider two body scattering processes elastic as well as inelastic. There are entry channels, i.e. the incoming…
Abhijit
- 522
14
votes
1 answer
BCS-BEC crossover
It would be really helpful if somebody could describe what does one mean by a BEC-BCS Crossover. I was going through articles available on the topic, but I was unable to grasp the gist of the topic.
Abhijit
- 522
13
votes
2 answers
A pendulum in a superfluid
Imagine to submerge a pendulum in a supefluid. Of course we assume an ideal pendulum, whose joint does not freeze or deteriorate due to the extremely low temperature. We also assume the superfluid to be at zero temperature, so we can neglect its…
AndreaPaco
- 1,322
13
votes
2 answers
Are all bose-einstein condensates superfluid?
I feel like the answer should be "no" since all superfluids are not strictly BEC since they can undergo a Kosterlitz–Thouless transition in 2D, for example. I believe the ideal gas isn't superfluid, but is there any experimental evidence of a BEC…
zje
- 233
12
votes
3 answers
What does the term liquid mean in condensed matter physics?
In condensed matter physics, people always say quantum liquid or spin liquid. What does liquid mean?
Brioschi
- 1,055
11
votes
1 answer
Do we have magnetic monopole? Is charge, according to yesterdays paper on Nature by Ray-Roukokoski-Kandel-Möttönen-Hall (30.01.14) quantized?
As everybody here knows, Maxwell's equation would look more beautiful if a magnetig charge were present. Beyond the aesthetics question, if a single magnetic Dirac monopole would be found, the consequence is that the electric charge would be…
c.p.
- 1,564