Tuesday, November 9 2021
9:30 - 10:45

IMSc Webinar

Neutral Excitations of Quantum Hall States: a Density Matrix Renormalization Group Study

Prashant Kumar,Department of Physics, Princeton University

We use the dynamical structure factors of the quantum Hall states
at $
u=1/3$ and $
u=1/2$ to study their excitation spectrum. Using the
density matrix renormalization group in combination with the time-dependent
variational principle on an infinite cylinder geometry, we extract the low
energy properties. At $
u=1/3$, a sharp magnetoroton mode and the
two-roton continuum agree with the fractionally charged quasi-particles
picture. At $
u=1/2$, we find low energy modes with linear dispersion and
the static structure factor $\bar s(q) \sim (q\ell)^3$ in the limit $q\ell
\rightarrow 0$. The properties of these modes can be explained by a
quasi-1D composite-fermion theory.

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