1,379 reputation
216
bio website
location Nanjing, China
age 27
visits member for 1 year, 9 months
seen Nov 18 at 14:41

I'm a graduate student studying theoretical condensed matter physics in Nanjing university, China.

My current interest is in the topics of symmetry, gauge theory, and topology in condensed matter theory.


Nov
18
revised Can we use combined symmetry to simplify the calculation of algebraic PSGs?
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Nov
18
asked Can we use combined symmetry to simplify the calculation of algebraic PSGs?
Nov
14
awarded  Popular Question
Nov
5
comment Symmetry, gauge, and projective symmetry group (PSG)?
Another simple formula: If $G_UU\in PSG(H)$, then $G_{U^{-1}}=U^{-1}G_U^{-1}U$ such that $G_{U^{-1}}U^{-1}\in PSG(H)$.
Nov
5
revised Symmetry, gauge, and projective symmetry group (PSG)?
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Nov
4
revised Symmetry, gauge, and projective symmetry group (PSG)?
added 424 characters in body
Nov
3
asked Symmetry, gauge, and projective symmetry group (PSG)?
Oct
26
comment Simple questions on the symmetric eigenstate and time-reversal (TR) breaking eigenstate?
@luming Thanks for your comment. $\psi_1\pm \psi_2\neq 0$ because $\psi_1$ and $\psi_2$ are two linear independent eigenstates.
Oct
25
asked Simple questions on the symmetric eigenstate and time-reversal (TR) breaking eigenstate?
Sep
30
awarded  Explainer
Sep
24
awarded  Autobiographer
Sep
19
comment Is there a critical order of the Abelian gauge theory in (2+1)D
@Everett You Dear Everett, I have a naive comment here. I don't know whether the group $Z_n$ has a well-defined limit $\lim_{n\rightarrow \infty}Z_n$ at the mathematical level. For example, if $Z_n\equiv \left \{exp(il\frac{2\pi}{n});l=1,2,...,n\right \}$, then it seems that $\lim_{n\rightarrow \infty}Z_n=U(1)$; while, if $Z_n\equiv \left \{ (-\frac{n}{2})^*,(-\frac{n}{2}+1)^*,...,0^*,1^*,2^*,...,(\frac{n}{2}-1)^*\right \}$($n$ is even for example), where $m^*\equiv \left \{ m,m\pm n,m\pm 2n,...\right \}$, then it seems that $\lim_{n\rightarrow \infty}Z_n=Z$($Z$ represents all the integers).
Sep
19
comment Some questions about anyons?
I'm sorry that I just saw your answer, thank you. I can not understand your explanation immediately, but I just found a related article.
Aug
6
comment Naive questions on the concept of effective Lagrangian and equations of motion?
I think I can answer my Q3 now: Classically, without the path integral method, express $x$ in terms of $E$ by solving the Euler-Lagrangian equation for $x$ derived from the total Lagrangian $L$, then substitute $x$ back into $L$, and we will obtain the same effective Lagrangian $L_{eff}$ containing only $E$.
Aug
4
comment Naive questions on the concept of effective Lagrangian and equations of motion?
And mathematically speaking, $OE=0$ does not always give the correct equation of motion. For example, let's take $O=\partial _t$, then $OE=0$ gives the equation $\partial _tE=0$, while the Euler-Lagrangian equation gives a trivial equation $\partial _tE=\partial _tE$. And here $O=\partial _t$ is NOT positive.
Aug
4
comment Naive questions on the concept of effective Lagrangian and equations of motion?
If $O$ is not positive, then there exists a function $f(t)$ such that $\int dtfOf<0=\int dtEOE$, where $OE=0$, which means that the solution $E$ does NOT correspond to the minimal action $S_{eff}$.
Aug
3
comment Naive questions on the concept of effective Lagrangian and equations of motion?
:Inspired by your comment, if there exists a least action principle for the effective action $S_{eff}=\int dtL_{eff}$, and further the operator $O$ is assumed to be positive, then $OE=0$ may be one possible solution. So what's your opinion?
Aug
2
comment Naive questions on the concept of effective Lagrangian and equations of motion?
♦ Yes. And I wonder whether we could define an effective Lagrangian containing only the electric field $E$ from the classical point of view? Thanks.
Aug
2
revised Naive questions on the concept of effective Lagrangian and equations of motion?
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Aug
2
comment Naive questions on the concept of effective Lagrangian and equations of motion?
♦ Thanks for your answer. You have given the classical equations of motion using normal coordinates. But I'm not interested in how to solve the classical harmonic oscillators, instead, here what I concerned is the concept of effective Lagrangian, either quantum version or classical version.