ULTRAQUEST · Ultrafast quantum transport in nanosystems controlled via phase-locked single cycles of light

Ultrafast quantum transport in nanosystems controlled via phase-locked single cycles of light

The aim of the project consists in starting new experiments in which the absolute optical phase of quasi single-cycle light pulses is harnessed to directly control charge transport in quantum nanosystems. The basic concept of this technique relies on the fact that, with ultrashort pulsed laser sources, it is possible to obtain extremely high peak intensities and thus high peak electric fields. Such pulses can be focused on a nano-scale junction of an electronic circuit. The strong field then allows symmetry breaking of the electronic band structure and triggers charge tunneling from one side of the junction to the other one through the potential barrier of the dielectric medium. Since this effect depends nonlinearly on the bias field, a net current results in the limit of phase-locked excitation pulses thus giving rise to temporal resolution and control on the sub-cycle timescale. The ultimate goal of the project is the development of a new technique and experiments that allow the optical control of current injection in confined nanosystems on an ultrafast timescale by using light pulses that approach the limit of a single optical cycle. Indeed, this is a completely new perspective in ultrafast sciences since traditional spectroscopies can be performed by relying only on all-optical triggering methods. Such techniques have allowed studying light-matter interaction on the femtosecond (10^-15) timescale prompting the field of femtochemistry. Recently, also the possibility to observe phenomena that occur within a few attoseconds has been introduced, thus opening the horizons of attophysics. On the other hand, the possibility to directly control charge movement is still limited by the speed of electronic components and it is difficult to observe electronic transport phenomena in solid-state nanostructures on a timescale faster than a few picoseconds. During the course of the project we established the new experimental technique in which the absolute optical phase of single-cycle light pulses is harnessed to directly control charge transport in nanostructured condensed matter, under conditions limited only by the intrinsic quantum processes.

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