Statistics of Coulomb Blockade Peak Spacings

Distributions of Coulomb blockade peak spacings are reported for large ensembles of both unbroken (magnetic field $B\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$) and broken ( $B\ensuremath{\ne}0$) time-reversal symmetry in GaAs quantum dots. Both distributions are symmetric and roughly Gaussian with a width of $\ensuremath{\sim}2%\char21{}6%$ of the average spacing, with broad, non-Gaussian tails. The distribution is systematically wider at $B\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ by a factor of $\ensuremath{\sim}1.2\ifmmode\pm\else\textpm\fi{}0.1$. No even-odd spacing correlations or bimodal structure in the spacing distribution is found, suggesting an absence of spin degeneracy. There is no observed correlation between peak spacing and peak height.