The world of attoseconds - Where a second lasts as long as the age of the universe

The observation of ultrafast fundamental processe in real time is a key to exploring the dynamic behaviour of matter. In order to be able to do these observations, pulses shorter than the processes under scrutiny have to be generated. Over the past decade novel ultrafast optical technologies have pushed the duration of laser pulses close to its natural limit, to the wave cycle, which lasts somewhat longer than one femtosecond (1 fs = 10EXP-15 s) in the visible spectral range. About ten years ago these pulses were used to generate single isolated attosecond pulses in the extreme ultraviolet (XUV): Atoms exposed to a few oscillation cycles of intense visible or near-infrared light are able to emit a single electron and XUV photon wavepacket of sub-femtosecond duration. Precise control of these sub-femtosecond wavepackets have been achieved by full control of the electromagnetic field in few-cycle light pulses. These XUV pulses together with the few-cycle (few-femtosecond) laser pulses used for their generation have opened the way to the development of a technique for attosecond sampling of electrons ejected from atoms or molecules and solids.