Real-time detection of single electron tunneling using a quantum point   contact
  We observe individual tunnel events of a single electron between a quantum dot and a reservoir, using a nearby quantum point contact (QPC) as a charge meter. The QPC is capacitively coupled to the dot, and the QPC conductance changes by about 1% if the number of electrons on the dot changes by one. The QPC is voltage biased and the current is monitored with an IV-convertor at room temperature. We can resolve tunnel events separated by only 8 $\mu$s, limited by noise from the IV-convertor. Shot noise in the QPC sets a 25 ns lower bound on the accessible timescales. 
L.M.K. Vandersypen, J.M. Elzerman, R.N. Schouten, L.H. Willems van   Beveren, R. Hanson and L.P. Kouwenhoven (Kavli Institut...