Questions tagged [research-level]

The research-level tag applies to questions that arise in graduate and post-secondary work. These questions often require domain-specific knowledge and could not be answered from a general source or may be beyond the level typically covered by Wikipedia and other popular sources. Research-level questions should not require new or groundbreaking research and results to answer.

Filter by
Sorted by
Tagged with
1
vote
0answers
25 views

What is the role of metric transitivity in statistical mechanics?

I was reading a paper of E.T. Jaynes 'Information Theory and Statistical Mechanics'. There he mentions the following principle in the section 'Application to Statistical Mechanics': The link to paper ...
-1
votes
1answer
84 views

Isn't Big Bang theory a violation of law of conservation of linear momentum?

What Big Bang theory assumed in the formation of universe? Answer:-At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion ...
0
votes
0answers
20 views

What is the relationship between discrete time quantum walk and Bessel functions?

From the paper Distributions of continuous-time quantum walks by Bessen, it is clear that the wavefunction for a continuous-time quantum walk at a later time $t$ follows Bessel functions. $$| \psi (t)\...
0
votes
0answers
42 views

If a particle can exert a force on itself,then can we define a whole lot of newtonian mechanics corresponding to it?

I think that it may be a broad question to be answered but if small amount of discussion is possible then it would be very helpful for all of us. Basically,I asked a question on this website a few ...
1
vote
1answer
143 views

What is the significance of noise which appeared in the experiments conducted by IISC students on superconductivity at room temperature? [closed]

A pair of Indian scientists may have just discovered the first superconductor material that works at room temperature. Their finding – which is currently surrounded by controversy – comes ten months ...
0
votes
0answers
19 views

What is air band and band gap in Photonic crystal structure?

want to know the meaning of air band of photonic crytal
3
votes
0answers
83 views

Calculate the matrix size for ground states BEC using difference with Gross–Pitaevskii equation

The Ground states BEC at $0$ temperature can be described by Gross–Pitaevskii equation as $(-\frac{\hbar^2}{2m}\nabla^2+V(r)+g|\psi|^2)\psi(r)=\mu\psi(r)$ We limit the BEC in 2D where $V(r)=\frac{1}{...
0
votes
0answers
15 views

what is bolch optical mode?

I have read some papers(https://arxiv.org/ftp/arxiv/papers/1206/1206.4342.pdf) where the word ''bolch mode'' used. Now I want to know what kind of optical mode this is and how or why it is generated?
6
votes
1answer
143 views

What classifies gaugings?

Gauging a global symmetry $G$ introduces several free parameters to the theory. For example, In $d=4$, gauging a simple and simply-connected Lie group introduces a coupling constant and a theta term, ...
1
vote
0answers
12 views

Comparision of using two dimensional mode or one dimensional in case of optical data transmission

Many works have been done to increase capacity of optical communication. I saw that some researcher using 1-D mode ,some 2-D to implement their device.The reson of using 1-d/2-d beacuse of their types ...
0
votes
1answer
15 views

What is the relationship of optical mode and data?

This question is on the plot of mode division multiplexing system where it is said capacity crunch can be solved using mdm technique. Now, we know single mode fiber can transmit upto 1Tbps. Now if i ...
1
vote
1answer
34 views

By how much are various dibaryon states unbound?

It has been known for a long time that the deuteron is stable but the dineutron (nn) and diproton (pp) are not. Many textbooks comment on this, but all the ones I found so far do not give quantitative ...
3
votes
1answer
190 views

Lindblad and Input-Output Formalism in Quantum Optics

I'm confused about how to apply the Lindblad formalism and the input-output formalism in practice, and how one goes between the two. Suppose I have a cavity (C) coupled to a reservoir (R), with the ...
9
votes
1answer
109 views

How many times do solar protons repeatedly fuse and fission before they form deuteron

In the proton-proton chain reaction in the Sun, the first step is $$p + p \rightarrow \; ^2_2{\rm He} .$$ After this, the most likely thing to happen next is that the reverse reaction occurs: the $^...
3
votes
1answer
237 views

How does physics research work? [closed]

I am going to try and be as short and as concise as possible. I was thinking these last few days about how we're still trying to discover a unified Theory of Everything. The question is: how is this ...
0
votes
0answers
42 views

Maxwell-Chern-Simons equation: Translating from differential form to component form

I am trying to solve the scalar-coupled Maxwell-CS equations (which is one of the equation of motions in $N=2$ supergravity coupled to 3 vector multiplets), which is written in this form in the ...
1
vote
0answers
38 views

Vandermonde determinant factor in supersymmetric gauge localisation computation

I am trying to learn supersymmetric localisation computation in which the path integral of a supersymmetric gauge theory (placed on a sphere) can be localised exactly to a BPS configuration ...
0
votes
0answers
21 views

Loschmidt Amplitudes In Tight Binding Models

I am trying to understand the calculation in this paper which experimentally looks at dynamical phase transitions in a driven (shaken) haldene-like model. The definition of the Loschmidt Amplitude is ...
1
vote
0answers
64 views

How exactly does a spin TQFT depend on the spin structure?

Take a spin Chern-Simons TQFT, such as $U(N)$ or $SO(N)$ with odd level. Such system depends on the spin structure of the underlying manifold. But how exactly does the theory depend on the spin ...
3
votes
0answers
62 views

Can you do gauge theories over topological groups?

Quantum gauge theories involve (functional) integration over a Lie group. Is there any meaningful generalisation to (non-manifold) topological groups? Consider for example the Whitehead tower $$ \...
3
votes
0answers
61 views

What is the topological data for $(\mathbb Z_n)_p$ theories?

Consider the 3d TQFT described by the Lagrangian (Dijkgraaf-Witten with gauge group $\mathbb Z_n$ at level $p$): $$ \mathcal L=\frac{n}{2\pi} B\wedge\mathrm dA+\frac{p}{4\pi}A\wedge\mathrm dA $$ with $...
1
vote
0answers
24 views

what is the advantages of using 2-μm operating wavelength light in sdm/mdm technology? [closed]

Most of the work have been done in the communication band but recently there has been emerging interest in extending the operating wavelength of communication system to the short-wave infrared (2 μm). ...
2
votes
1answer
302 views

what is effective index method which is used to solve modes in rectangular waveguide? [closed]

I actually want to know the basics of effective index methods for solving the optical modes in slab/rectangular waveguides.
2
votes
0answers
164 views

Are broken time reversal symmetry and inversion symmetry forbidden in a Weyl semimetal?

In much of the literature floating around, it is commonly implied that an important part of obtaining a Weyl semimetal phase is to break either time reversal symmetry or inversion symmetry. However, ...
11
votes
2answers
363 views

Are there aspects of General Relativity that have yet to be tested?

Good evening everyone, I am new in the field of General Relativity and I have been reading and learning about the subject in recent months. For example, I read several articles about experiments ...
3
votes
0answers
68 views

What is meant by this variant of the euclidean plane: $\mathbb{R}^2_{\hbar}$?

I am reading some papers in mathematical physics (https://arxiv.org/abs/1006.0977) and I came across the following symbol $\mathbb{R}^2_{\hbar}$ I don't recognize nor could I find any background ...
1
vote
0answers
30 views

Reference on discussion about the distinction among Schwarzschild vacua

In Schwarzschild spacetime there are a couple of "vacuum" states: the Boulware vacuum, the Unruh vacuum and the Hartle-Hawking vacuum. I actually don't know if there are others. This is something ...
6
votes
1answer
397 views

“Weak” and “Strong” topological insulators

For translationally invariant systems, we can define some topological invariant based on the translational symmetry, which is referred to "weak" topological invariant. For example, according to Kitaev'...
3
votes
1answer
67 views

Does a SUSY Chern-Simons term prevent the dualising of the gauge potential to a scalar?

In 3D $\mathcal{N}=2$ supersymmetric field theory with abelian gauge fields, the gauge field $A_{\mu}$ is often dualised to a real scalar $\gamma$. Does a Chern-Simons term prevent this dual ...
2
votes
1answer
149 views

In 3D ${\cal N}=2$ SUSY, the linear multiplet contains a global current. How is this related to the gauge field?

I am reading the paper on 3d $\mathcal{N}=2$ supersymmetry by O. Aharony et al. (https://arxiv.org/abs/hep-th/9703110) and I am a bit confused about linear multiplets in section 2.3. A linear ...
5
votes
1answer
338 views

Truncation of $D=5$, ${\cal N}=8$ Supergravity by $\mathbb Z_2^3$

The scalar manifold of $D=5, \mathcal N=8$ SUGRA is $$\mathcal M = \frac{E_{6(6)}}{Usp(8)}$$ where $USp(8)$ is a maximal compact subgroup of $E_{6(6)}$ and the 42 scalars of the theory correspond ...
5
votes
2answers
222 views

How Quantum Information can be important for fundamental physics?

It seems that Quantum Information has been seriously considered as something very important for fundamental physics, and in particular, to quantum gravity. For example, this is the topic of this ...
1
vote
1answer
71 views

Is this system somehow one toy model for something more complicated?

Sometimes in Physics one builds a toy model to study some more complicated phenomenon. One example would be the Gross-Neveu model and its relation to QCD. Now, consider the following situation in the ...
3
votes
1answer
101 views

Why is the flux quantized in 4D quantum Hall effect?

I am reading "Topological Field Theory of Time-Reversal Invariant Insulators" by Qi, Hughes, and Zhang (https://arxiv.org/abs/0802.3537). It argues that time reversal invariant (TRI) insulators in 2+1 ...
8
votes
1answer
195 views

Allowed anyons for Chern-Simons at level $k.$

Ref.1. proves that the allowed representations of Chern-Simons $\mathrm{SU}(2)_k$ are those with dimension $$ \dim(R)\le k+1\tag{7.53} $$ Question: Is the generalisation of $(7.53)$ to arbitrary $N$ ...
4
votes
1answer
269 views

Relation between cobordism and unitary fusion category classification of TQFT/ SPT phase

In the introduction part of Gaiotto's paper (https://arxiv.org/pdf/1712.07950.pdf), he says "in the context of topological field theory, homotopy-theoretic ideas also lead to the classification of ...
2
votes
1answer
113 views

Peskin's duality in XY model (Mandelstam-'t Hooft duality in abelian lattice models)

I am studying the old paper by Peskin (1978): Mandelstam-'t Hooft duality in abelian lattice models (https://doi.org/10.1016/0003-4916(78)90252-X). However, I am confused about some details of ...
3
votes
1answer
128 views

Relationship between different $Z_{16}$ classifications

I find that there exist two classifications which have a $Z_{16}$ group structure: The sixteen fold way of classifying Majorana fermions, vortex systems appearing in Kitaev's paper on his honeycomb ...
1
vote
1answer
129 views

What is the actual importance of Dixon's extended bodies theory for fundamental physics?

Disclaimer: I'm unsure if this question fits here. If it doesn't please let me know if it can be modified so that it does. In the end if it simply doesn't fit here, I'll delete it. The motivation for ...
1
vote
0answers
32 views

On the optimality of Stabilizer codes

I have been studying about quantum error correction codes, specifically aobut the so-called stabilzer codes, and I wonder if are this class of quantum codes the best codes known (in terms of capacity ...
10
votes
1answer
699 views

On a rigorous definition of Feynman's functional integral$.$

It is often stated that there is no mathematically rigorous definition of Feynman's functional integral, except for some very specific examples. I may be very naïve, but to me there is at least one ...
3
votes
0answers
91 views

How to get the eigenvalue density contribution $\rho_1(x)$?

I'm studying the $1/N$ expansion beyond the planar limit in matrix models. Currently I'm trying to understand and reproduce the results of: Antisymmetric Wilson loops in $\mathcal N \geq 4$ SYM ...
2
votes
1answer
123 views

Hawking radiation on Kruskal-Szekeres coordinates

Recently a physicist I know said he was interested in the following question: "would one observer following Kruskal-Szekeres coordinates in the presence of a Schwarzschild black hole (i.e., whose ...
1
vote
0answers
121 views

Producing double-slit interference in string theory

My full question is What brane configuration most economically reproduces a double-slit interference effect? It was inspired by this question, which asks whether string theory has anything to say ...
4
votes
0answers
174 views

Different definitions of topological phases

When doing classification of topological phases, one need to formalize the problems mathematically. But, it seems that there are two not obviously equivalent ways to describe topological phases. In ...
4
votes
1answer
1k views

Ground state degeneracy: Spin vs Fermionic language

Let us first consider the Hamiltonian of well-known 1D periodic Ising model as $$ H = -\frac{1}{2} \sum_{j=1}^N \sigma^x_j \sigma^x_{j+1} + \frac{h}{2}\sum_{j=1}^N \sigma^z_j. $$ Now, in the ...
1
vote
0answers
96 views

Research about extended bodies in Einstein-Cartan gravity

There is out there an approach to deal with extended bodies in General Relativity due to Dixon that seems to be quite well known and believed to be the correct way to describe such phenomena on this ...
4
votes
1answer
144 views

Wightman's theorem, in terms of time-ordered functions$.$

According to Wightman's theorem, given a set of distributions $\{W_n\}$ satisfying a set of axioms, we may conclude the existence of a set of operators $\{\phi\}$ which satisfy some properties, and ...
3
votes
0answers
67 views

Books for studying non-linear dynamics [closed]

I've recently developed interest into non-linear dynamics and chaos theory after having read a large part of the book by Steven Strogatz. Is it possible for me to delve into a research area dealing ...
2
votes
1answer
139 views

Quark condensate alignment with Yukawa Higgs couplings

It is well known in QCD that the light quark condensates are a unit matrix in flavor space: $\langle \bar{u}u\rangle=\langle \bar{d}d\rangle=\langle \bar{s}s\rangle\sim\Lambda_{\rm QCD}^3$. Thus, we ...