The study of physical properties condensed phases of matter, including solids and liquids.
21
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2answers
167 views
Renormalization Group for non-equilibrium
For equilibrium/ground state systems, a (Wilson) renormalization group transformation
produces a series of systems (flow of Hamiltonians/couplings $H_{\Lambda}$ where $\Lambda$ is the cut-off) such ...
19
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5answers
2k views
Do photons gain mass when they travel through glass?
Please correct me if I'm wrong, but I believe that photons slow down when travelling through glass. Does this mean they gain mass? Otherwise, what happens to extra kinetic energy?
I understand now ...
18
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1answer
782 views
How Fundamental is Spin-Orbit Coupling to Topological Insulators?
I'm well aware this is a very active area of research so the best answer one can give to this question may be incomplete.
Topological states in condensed matter are well-known, even if not always ...
17
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10answers
1k views
What is spontaneous symmetry breaking in QUANTUM systems?
Most descriptions of spontaneous symmetry breaking, even for spontaneous symmetry breaking in quantum systems, actually only give a classical picture.
According to the classical picture, spontaneous ...
16
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2answers
259 views
Edge theory of FQHE - Unable to produce Green's function from anticommutation relations and equation of motion?
I'm studying the edge theory of the fractional quantum Hall effect (FQHE) and I've stumbled on a peculiar contradiction concerning the bosonization procedure which I am unable to resolve. Help!
In ...
15
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5answers
1k views
Simple models that exhibit topological phase transitions
There are a number of physical systems with phases described by topologically protected invariants (fractional quantum Hall, topological insulators) but what are the simplest mathematical models that ...
15
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3answers
891 views
Are elementary particles actually more elementary than quasiparticles?
Quarks and leptons are considered elementary particles, while phonons, holes, and solitons are quasiparticles.
In light of emergent phenomena, such as fractionally charged particles in fractional ...
13
votes
3answers
1k views
Good reading on the Keldysh formalism
I'd like some suggestions for good reading materials on the Keldysh formalism in a condmat context. I'm familiar with the imaginary time, coherent state, path integral formalism, but lately I've been ...
13
votes
4answers
1k views
Quantum Hall effect for dummies
In the past few days I've become increasingly intrigued by the QHE, mainly thanks to very interesting questions and answers that have appeared here. Unfortunately, I am as of yet very confused by all ...
12
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4answers
2k views
A pedestrian explanation of conformal blocks
I would be very happy if someone could take a stab at conveying what conformal blocks are and how they are used in conformal field theory (CFT). I'm finally getting the glimmerings of understanding ...
12
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3answers
281 views
Why are so many condensed matter phenomena so dependent upon impurities?
Why are so many condensed matter phenomena so sensitive to impurities? In fact, quite a number of them depend upon impurities for their very existence!
12
votes
2answers
1k views
What is a resonating valence bond (RVB) state?
There's something known as a "resonating valence bond" (RVB) state, which plays a role in at least some attempts to understand physics of high-$T_c$ superconductors. This, roughly, involves a state ...
12
votes
3answers
562 views
Shine a light into a superconductor
A type-I superconductor can expel almost all magnetic flux (below some critical value $H_c$) from its interior when superconducting. Light as we know is an electromagnetic wave. So what would happen ...
11
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5answers
2k views
What does it mean for a Hamiltonian to be gapped?
I've read some papers recently that talk about gapped Hamiltonians or gapless systems, but what does it mean?
Edit: Is an XX spin chain in a magnetic field gapped? Why or why not?
11
votes
2answers
131 views
Literature on fractal properties of quasicrystals
At the seminar where the talk was about quasicrystals, I mentioned that some results on their properties remind the fractals. The person who gave the talk was not too fluent in a rigor mathematics ...
11
votes
1answer
51 views
Limitations in using FLEX as a DMFT solver
When using the fluctuating exchange approximation (FLEX) as a dynamical mean field theory (DMFT) solver, Kotliar, et al. (p. 898) suggest that it is only reliable for when the interaction strength, ...
11
votes
3answers
630 views
Phonons in non-crystalline media
Do sound waves in a gas consist of phonons?
What about a glass? Or other non-crystalline materials such as quasicrystals?
How does the lack of translational symmetry affect the quantization of the ...
11
votes
3answers
847 views
Condensed matter application of AdS/CFT
I'm going to be teaching a course on gauge/gravity duality (aka AdS/CFT) in the winter.
The focus will be on applications in particle theory including $N=4$ SYM, the viscosity/entropy bound, and ...
11
votes
1answer
433 views
Emergent symmetries
As we know, spontaneous symmetry breaking(SSB) is a very important concept in physics. Loosely speaking, zero temprature SSB says that the Hamiltonian of a quantum system has some symmetry, but the ...
10
votes
2answers
489 views
Basic questions in Majorana fermions
Why any fermion can be written as a combination of two Majorana fermions? Is there any physical meaning in it? Why Majorana fermion can be used for topological quantum computation?
10
votes
2answers
353 views
Why quantum hall effect has chiral edge state?
The most popular explaination may be the following: in magnetic field, electrons move in cycolotron orbits, such cycolotron orbits ensure electrons to move in one direction at the edge. That is why ...
10
votes
1answer
79 views
Consideration of static atomic displacements in electronic structure calculations
I am hoping to discuss some details of electronic structure calculations. I am not an expert on this topic, so please forgive any abuse of terminology. It is my understanding that first principles ...
10
votes
2answers
290 views
What is known about some massive Gaussian models on a lattice?
Recently I started to play with some massive Gaussian models on a lattice. Motivation being that I work on massless models and want to understand the massive case because it seems easier to handle ...
10
votes
2answers
264 views
Is there a way to directly observe the spin texture of the surface states of topological insulators?
Is there a way to directly, here I means in real space, observe the interaction of the surface states of 3D topological insulators with defects (dopings and adatoms)? How to observe the spin texture ...
9
votes
6answers
250 views
optical equivalent of a superconductor
Is there some material state that can propagate light indefinitely without dissipation or absorption, like superconductors are able to trasmit current indefinitely?
If not, then the question is, why ...
9
votes
3answers
335 views
Introduction to Anderson localization [closed]
I find Anderson's original paper too terse. I am looking for something that introduces me gently to the subject so that I can understand Anderson's paper and other literature. What references are out ...
9
votes
2answers
923 views
trying to understand Bose-Einstein Condensate (BEC)
I am a computer scientist interested in network theory. I have come across the Bose-Einstein Condensate (BEC) because of its connections to complex networks. What I know about condensation is the ...
9
votes
1answer
120 views
Is the liquid/solid line infinite?
Starting from the triple point, is the melting line between solid-phase and liquid-phase infinite? If not, why does it end? Because pressures are so high that classical inter-molecular interactions ...
9
votes
1answer
849 views
Has Chandra Varma explained cuprate superconductivity?
Chandra Varma is a theoretical physicist at University of California, Riverside. A couple years ago, he gave a talk at my institution purporting to explain superconductivity in the cuprates. It all ...
9
votes
1answer
360 views
What are some predictions from string theory that say some crystalline materials “will end up in one of many lowest-energy ground states?”
I am referring to this recent "news feature" by Zeeya Merali from Nature magazine www.nature.com/uidfinder/10.1038/478302a. Here is the specific quote:
"To make matters worse, some of the testable ...
9
votes
1answer
173 views
Lagrangian for Goldstone mode + topological excitation
The XY-model Hamiltonian is the following,
$${\cal H}~=~-J\sum_{\langle i,j\rangle} \cos (\theta_i -\theta_j).$$
The Goldstone mode corresponds to term $(\nabla \theta)^2$ in the effective ...
9
votes
1answer
105 views
Why are topological solitons present in some phases for lattice models?
Over a spatial continuum, it is easy to see why some topological solitons like vortices and monopoles have to be stable. For similar reasons, Skyrmions also have to be stable, with a conserved ...
9
votes
1answer
193 views
What is the “BCS Cooper pair condensation” as a physical phenomenon in terms of experiments?
"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 recent research on ...
8
votes
3answers
273 views
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?
8
votes
3answers
189 views
References on the physics of anyons
Anyone know some good introductory references on the physics of anyons?
8
votes
1answer
1k views
Spontaneous Time Reversal Symmetry Breaking?
It is known that you can break P spontaneously--- look at any chiral molecule for an example. Spontaneous T breaking is harder for me to visualize. Is there a well known condensed matter system which ...
8
votes
5answers
473 views
I found it strange in case of an egg omlette
Its known to everyone that when a solid is heated up to its melting point it turns into a liquid. What happens when a liquid is heated? Simple, it tends towards becoming gaseous.
While making omlettes ...
8
votes
2answers
1k views
How do Dirac fermions arise in graphene, and, what significance (if any) does this have for high-energy physics?
Graphene has a honeycomb lattice (in the absence of defects and impurities). By considering the low-energy limit of the half-filled Hubbard model used to model the strongly interacting electron gas we ...
8
votes
1answer
120 views
What're the relations and differences between slave-fermion and slave-boson formalism?
As we know, in condensed matter theory, especially in dealing with strongly correlated systems, physicists have constructed various "peculiar" slave-fermion and slave-boson theories. For example,
For ...
8
votes
2answers
396 views
What is the mathematical reason for topological edge states?
There are many free fermion systems that possess topological edge/boundary states. Examples include quantum Hall insulators and topological insulators. No matter chiral or non-chiral, 2D or 3D, ...
8
votes
1answer
173 views
Resistance of a two-dimensional sample
In this review of the QHE, Steve Girvin makes the following statement (bottom of pg. 6, beginning of Sec. 1.1.1):
As one learns in the study of scaling in the localization transition, resistivity ...
8
votes
1answer
383 views
Interpretation of the Random Schrödinger Equation
I should preface this by admitting that my physics background is rather weak so I beg you to keep that in mind in your responses. I work in mathematics (specifically probability theory) and a paper ...
8
votes
1answer
118 views
What is Anderson localization? Could someone give an example worked out in detail?
What is Anderson localization, for someone with no previous knowledge on the subject?
I tried to read Anderson's original paper, but it was too terse for me. I have seen a couple of intuitive ...
8
votes
1answer
307 views
Kramer's-Kronig relations for the electron Self-Energy Σ
I'm currently studying an article by Maslov, in particular the first section about higher corrections to Fermi-liquid behavior of interacting electron systems. Unfortunately, I've hit a snag when ...
7
votes
2answers
828 views
How can rising bubbles shrink and disappear?
I was recently looking at a Wurlitzer juke box, and noticed something strange. It's decorated with liquid-filled tubes. Gas bubbles are injected at the bottoms of the tubes, and the bubbles naturally ...
7
votes
2answers
429 views
How far away are we from resolving high temperature superconductivity?
What are the major recent findings and their corresponding contributions to an overall picture?
How well explained are the various regions of the dome, is there any thing that is pretty well ...
7
votes
1answer
377 views
A better conceptual model for cooper pairs in a superconductor
The conceptual model I have been introduced to for cooper pairs in a bulk superconductor is what I would call the "wake" model, where one electron deforms the positively charged lattice, changing the ...
7
votes
1answer
3k views
Kubo Formula for Quantum Hall Effect
I'm trying to understand the Kubo Formula for the electrical conductivity in the context of the Quantum Hall Effect.
My problem is that several papers, for instance the famous TKNN (1982) paper, or ...
7
votes
3answers
358 views
Mathematical rigorous introduction to solid state physics
I am looking for a good mathematical rigorous introduction to solid state physics. The style and level for this solid state physics book should be comparable to Abraham Marsdens Foundations of ...
7
votes
2answers
321 views
What is the experimental status of AdS/CFT, AdS/QCD, AdS/CMT, etc?
What experiments have challenged or supported AdS/QCD, AdS/CMT, etc? What experiments should we look forward to do this?
