Physical Society Colloquium

Attosecond Science

Paul Corkum

NRC
Ottawa

A revolution is underway in ultrafast optical technology. During the past five years, the minimum pulse duration of optical pulses has fallen from 5 femtoseconds (5x10^-15 sec) to about 100 attoseconds (~10^-16 sec) — briefer than the classical period of a ground-state electron in a hydrogen atom.

Attosecond technology maps onto interferometry. Quantum mechanical tunneling in an intense laser field splits the electron. After tunneling, one component of the electron wave function is accelerated away from the ion by the laser field, but returns once the field reverses its sign. The other component remains bound to the ion. These two paths form the two arms of the interferometer. When the two components of the electron wave function overlap, they interfere. The interference leads to an oscillating dipole that produces attosecond optical pulses. Attosecond technology allows us to “see” electrons (in the sense that an optical interferometer “sees” light pulses).

I will describe how attosecond electron interferometry is used to image molecular orbitals and how it measures both the spatial and temporal properties of attosecond optical pulses.