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I am a postdoc at Kavli Institute for Theoretical Physics, University of California, Santa Barbara. My major is in condensed matter physics.


1d
reviewed Approve Q: Any standard terminology for “gold standard” Monte Carlo solutions
1d
reviewed Approve Given state cannot be written as a linear combination of pure states
1d
reviewed Approve How to calculate earth's magnetic field by time period of suspended magnet?
1d
reviewed Approve Maths behind gravity assist
1d
revised Does exciting an electron across the band gap change either its position or its localization?
added 477 characters in body
1d
answered Does exciting an electron across the band gap change either its position or its localization?
2d
answered “Bosons are either gapped or condensated, except physical principle protected cases (Goldstone boson, photon).”?
Apr
17
answered Why spin-1/2 objects doesn't have quadrupolar magnetic moment?
Apr
15
answered How to verify/falsify the existence of localised edge states numerically?
Apr
6
comment Interacting fermionic SPT phases in 2d with time-reversal symmetry
@KaiLi It does not make sense to write down a term like $c+c^\dagger$ in the Hamiltonian, because Hamiltonian must be a bosonic operator that corresponds to the energy of the system.
Apr
6
comment Interacting fermionic SPT phases in 2d with time-reversal symmetry
@KaiLi No, fermion number parity is not the particle hole symmetry in the classification table. All fermion systems have the fermion number parity conservation, but not all of them are particle-hole symmetric.
Apr
6
comment Interacting fermionic SPT phases in 2d with time-reversal symmetry
@KaiLi $T^2=-1$ is a projective representation of the $Z_2^T$ group on the fermions. The symmetry of the entire fermion system is still $T^2=+1$ because fermions must appear in pairs. This is just like in the PSG, when you have some 2-fold symmetry squared to -1, you tend to call it projective rep, other than group extension, although they are mathematically the same. If our universe is built from qubits, then fermion systems actually have topological order, so the -1 sign change of a single fermion can be gauged away, and should not be considered as a symmetry operation.
Mar
27
reviewed Approve How to derive (the dimensionless coefficient in front of) the moment of inertia for common shapes?
Mar
26
asked How to count the number of modes/polarizations of a Gaussian field theory?
Mar
26
comment Is there a 2D manifold on which the Dirac equation has a zero mode?
Thanks. So do you have an answer of the question, if we restrict to the Euclidian metric signature?
Mar
26
comment Is there a 2D manifold on which the Dirac equation has a zero mode?
@Qmechanic Thanks for your comment. The torus $T^2$ has no curvature, but still there is no zero mode of Dirac equation on $T^2$. Is there a scalar curvature indefinite 2D manifold, on which Dirac equation can have a zero mode?
Mar
26
comment Is there a 2D manifold on which the Dirac equation has a zero mode?
Do you mean that Dirac fermion can never have zero mode on any 2D manifold with Euclidian metric signature?
Mar
24
asked Is there a 2D manifold on which the Dirac equation has a zero mode?
Feb
27
revised What're the relations and differences between slave-fermion and slave-boson formalism?
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Feb
27
revised What're the relations and differences between slave-fermion and slave-boson formalism?
deleted 12 characters in body