Entanglement of two strongly correlated electrons in a lateral quantum dot

Exact-diagonalization calculations for two electrons in an elliptic lateral quantum dot show that the electrons can localize and form a molecular dimer even for screened interelectron repulsion. The calculated singlet-triplet splitting ($J$) as a function of the magnetic field ($B$) agrees with cotunneling measurements;\footnote{D.M. Zumb\"{u}hl {\it et al.\/}, Phys. Rev. Lett. {\bf 93}, 256801 (2004).} its behavior reflects the effective dissociation\footnote{C. Yannouleas and U. Landman, Int. J. Quantum Chem. {\bf 90}, 699 (2002)} of the electron dimer for large $B$. Knowledge of the dot shape and of $J(B)$ allows determination of two measures of entanglement (concurrence and von Neumann entropy for {\it indistinguishable\/} fermions), whose behavior correlates also with the dissociation of the dimer. The theoretical value for the concurrence at $B=0$ agrees with the experimental estimates.