20 Dec 2007
Femtosecond pulse stabilization captures attosecond electron transport in real time.
An international team at the Max Planck Institute of Quantum Optics in Germany has made the first attosecond measurement in condensed matter, which could lead to coherent control in solids on the atomic scale. It is a step towards electronics in which the speed is limited only by the time required for an electron to travel between neighboring atoms.
In the proof-of-principle experiment, pulses of extreme ultraviolet light of 300 attoseconds duration fell upon the surface of a tungsten crystal, along with an infrared pulse comprising a few well-controlled oscillation cycles of its electric field.
The ultraviolet photons excited both loosely-bound electrons and electrons bound tightly to the cores of the atoms forming the crystal lattice. The difference in arrival time of these two types of electron on the crystal surface was measured at 110 attoseconds, as resolved by the rapidly oscillating phase-stabilized infrared pulses.
The generation of the attosecond ultraviolet pulses and the detection of the released electrons on the surface both employed phase-stabilization technology developed by Menlo Systems. This technology can stabilize the phase of ultrashort-pulse high-power lasers to about 100 mrad over several hours.