  As a general trend, nanoelectronics experiments are shifting toward
frequencies so high that they become comparable to the device's internal
characteristic time scales, resulting in new opportunities for studying the
dynamical aspects of quantum mechanics. Here we theoretically study how a
voltage pulse (in the quantum regime) propagates through an electronic
interferometer (Fabry- Perot or Mach-Zehnder). We show that extremely fast
pulses provide a conceptually new tool for manipulating quantum information:
the possibility to dynamically engineer the interference pattern of a quantum
system. Striking physical signatures are associated with this new regime:
restoration of the interference in presence of large bias voltages; negative
currents with respect to the direction of propagation of the voltage pulse; and
oscillation of the total transmitted charge with the total number of injected
electrons. The present findings have been made possible by the recent unlocking
of our capability for simulating time-resolved quantum nanoelectronics of large
systems.
