Mardi 18 juin 2013 à 09h45
Salle 234, Ecole de Physique

A new on-demand electron source based on Lorentzian voltage pulses

Christian Glattli, CEA-Saclay, Paris

Generating pure quantum excitations is a key issue to operate quantum systems. For Fermions this is particularly difficult as a time dependent perturbation affects all states below the Fermi energy resulting in complex particles and holes excitations. However, a Lorentzian time dependent potential with quantized flux is expected to generate a time resolved minimal excitation with only one particle and no hole: a Leviton [1-3]. We report the experimental realization of on-demand generation of Levitons in a conductor by applying voltage pulses on a contact [4]. The injected charges are partitioned by an electronic beam-splitter whose current noise measures the excitation number. Minimal excitation states are observed for Lorentzian pulses while sine and square pulses show significant holes contribution. Hong-Ou-Mandel noise correlation of electron pulses emitted from independent contacts and shot noise spectroscopy further characterize the states in time and energy. These minimal excitation states open quantum applications for both atomic and electronic Fermion systems. [1] L. Levitov, H. Lee, and G. Lesovik, Electron counting statistics and coherent states of electric current. J. Math. Phys. 37, 4845 (1996) [2] D. A. Ivanov, H. W. Lee, and L. S. Levitov, Coherent states of alternating current. Phys. Rev. B 56, 6839 (1997) [3] J. Keeling, I. Klich, and L. Levitov, Minimal excitation states of electrons in one-dimensional wires. Phys. Rev. Lett. 97, 116403 (2006) [4] J. Dubois, T. Jullien, P. Roullleau, F. Portier, P. Roche, W. Wegscheider, A. Cavanna, Y Jin, and D.C. Glattli, submitted to Science