a) Schematic of the sample with As dopants in the source and drain in blue. For positive substrate bias and negative front gate voltages the electrons flow near the buried Si/SiO2 interface in the constriction between the front gates. Two P donors (P1, P2) are drawn in red in this region.
b) spectroscopy at Vd=16mV showing the ground state (base of the triangles) and the first excited state line at 10meV.
Two-atom electron pump
Experimental data of the pumped current in the non-adiabatic regime. All the characteristic features observed in this figure is explained by our model taking into account finite tunnel rates to the leads and a Landau-Zener transition between the two dopants.
We have realized electron pumping through two phosphorus donors in series implanted in a silicon nanowire. While quantized pumping is achieved in the low frequency adiabatic regime, we observe remarkable features at higher frequency when the charge transfer is limited by the different tunneling rates. The transitions between quantum states are modeled involving a Landau-Zener transition, allowing to reproduce in detail the characteristic signatures observed in the non-adiabatic regime. This work has been done in collaboration with Roman Riwar and Janine Splettstoesser in Aachen (RWTH) .
 Roche B, Riwar RP, Voisin B, Dupont-Ferrier E, Wacquez R, Vinet M, Sanquer M, Splettstoesser J and Jehl X
A two-atom electron pump.
Nature Communications, 2013, 4: 1581
Coherent, Landau-Zener-Stückelberg interferences
Coherent driving of the double-donor TLS. We observe sharply defined interference fringes.
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