Hidden quasisymmetry in the optical absorption of quantum dot nanorings

We report numerical results demonstrating the existence of a hidden dynamical quasisymmetry in the optical absorption of finite nanorings consisting of metallic quantum dots described by means of the extended Hubbard model for closed shells, causing, out of a multitude of transitions allowed by spatial symmetry, all but one to be practically forbidden. We show that, by shining only a part of the nanoring, one can get more information than by irradiating the whole nanoring, and suggest that experimentalists apply this method to measure optical absorption spectra.

Figure 1

(Color online) Ground-state properties versus interdot spacing $d$: (a) the weights $w_{\mathit{del}}$ and $w_{\mathit{loc}}$ corresponding to perfectly delocalized (SCF) and localized electrons (solid and dashed lines, respectively) in the neutral ground state of a nanoring with six and ten QDs. (b) Populations of MOs (symmetry indicated in the figure) for ten-QD nanorings. (Ref. 16)

Figure 2

(Color online) Spectral intensities for six- and ten-QD nanorings. Note the logarithmic scale.

Figure 3

(Color online) MO populations of the lowest $E_{1u}$ eigenstate for ten-QD nanorings (Ref. 16.

Figure 4

(Color online) Optical absorption spectra for ten-QD nanorings by irradiating (a) the entire ring and (b) only one QD computed at $d=1.1$, 1.2, 1.4, 1.6, and 1.7.