COHERENCE AND PHASE-SENSITIVE MEASUREMENTS WITH A QUANTUM-DOT

The subject of coherent versus sequential resonant tunnelling (RT) pro cess has been controversial for a long time (T. Well and B. Winter, Ap pl. Phys. Lett. B 50 (1987) 1281). We devised a novel interference exp eriment which determines conclusively the nature of transport - with s ome added surprises - through a submicron RT structure: a quantum dot in the Coulomb blockade regime (M.A. Kastner, Phys. Today 46 (1993) 24 ). In principle, this method allows the measurement of both the magnit ude and the phase of the transmission amplitude through any coherent m esoscopic structure.