Description |
We compute the neutral excitation spectra of ν=1/3 and ν=1/2 quantum Hall states on infinite cylinders of circumferences upto 10 magnetic lengths. At filling fraction ν=1/3, we find a magneto-roton mode that can be interpreted as a dipole-like bound state of a quasi-electron and a quasi-hole. At ν=1/2, the excitation spectrum contains linearly dispersing modes at small wave-vectors and a fan of excitations at 2KF. We compare our results with a quasi-1D composite-fermion (CF) theory and present compelling quantitative evidence for the emergence of CFs at low energies.
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