Condensation energy of a superconducting grain with N interacting electrons as a function of the coupling constant \lambda. The top, red, curve us the exact result within the Richardson model; the black one is the BCS result (note that the former is much larger than the latter in a substantial range of \lambda) and the blue curve is the parabolic approximation to the exact one. The scale of 1/ln N for \lambda, is identical to the lavel spacing being of the order of the BCS gap. The BCS result applies only for much larger grains. M. Schechter et al, Phys. Rev. B. 63, 214518 (2001); [cond-mat/0012160].

The density (~dark area) of electrons in the dot for nine levels. Dashed lines are the lines of constant potential V = 20,0, -20, -40, -60, and -80. The single-channel wire is attached from the left. About 95% of the norm of the wave function in the dot is shown. P. G. Silvestrov and Y. Imry, Cond-Mat/9911205vl 13 Nov 1999.

 Images of Selected Nano-Systems