[ExI] An advance in Nanotechnology

John Clark johnkclark at gmail.com
Thu Feb 6 22:26:32 UTC 2020

Atomic scale resolution has been achieved for several decades with Scanning
Tunneling Microscopes, they work by moving the tip of a super sharp needle
and measuring the tunneling current induced by quantum fluctuations. The
tunneling current is extremely sensitive to the distance between the needle
and the sample so you get excellent spatial resolution, but unfortunately
you also get very poor temporal resolution. In the January 24 2020 issue of
the journal Science Garg and Kern report on a way to overcome this problem,
they could get angstrom (10^-9 meter) level spatial resolution and
attosecond (10^-18 second) temporal resolution. They found that by
illuminating the tip of the needle with ultrashort Laser pulses they could
greatly enhance the induced tunneling current and, unlike the normal
tunneling current, it would have a well defined phase.

In addition the editors of Science speculate that "quantum computing
protocols might harness the coherent tunneling phase"  that Garg and Kern
have discovered.


*Nanoelectronic devices operating in the quantum regime require coherent
manipulation and control over electrons at atomic length and time scales.
We demonstrate coherent control over electrons in a tunnel junction of a
scanning tunneling microscope by means of precise tuning of the
carrier-envelope phase of two-cycle long (<6-femtosecond) optical pulses.
We explore photon and field-driven tunneling, two different regimes of
interaction of optical pulses with the tunnel junction, and demonstrate a
transition from one regime to the other. Our results show that it is
possible to induce, track, and control electronic current at atomic scales
with subfemtosecond resolution, providing a route to develop petahertz
coherent nanoelectronics and microscopy.*

Attosecond coherent manipulation of electrons in tunneling microscopy

John K Clark
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