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^-10 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.
John K Clark
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