The taming of electrons
The physicists at the Max Planck-POSTECH Center for Attosecond Science are seeking to realise an as yet unachieved degree of control over processes in the quantum world. They want to monitor and control the trajectories of electrons with the aid of ultrashort and very high intensity laser pulses, in order to not only be able to understand and control chemical reactions on the level of individual atoms and molecules, but to also set new standards for the speed of electronic components.
These aims can only be achieved with the tools of attosecond physics, as only laser pulses that last no longer than a few attoseconds, i.e. a few billionths of a billionth of a second, are brief enough to catch the extremely fast electrons - be it to observe their paths or to steer them. The team of researchers headed by Ferenc Krausz at the Max Planck Institute of Quantum Optics in Garching are the global leaders in this field.
At the Max Planck-POSTECH Center for Attosecond Science, the Garching-based Max Planck physicists are advancing attosecond physics together with researchers in Dong Eon Kim’s group at Pohang University of Science and Technology (POSTECH). Additionally, four other Max Planck institutes are involved at the Max Planck Center, for example the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg and the Fritz Haber Institute of the Max Planck Gesellschaft in Berlin, and four research facilities in the Asia-Pacific region, including the Institute for Physics of the Chinese Academy of Sciences and the Australian Attosecond Facility at Griffith University in Brisbane/Australia.
One of the aims of the joint activities is to expand the possibilities whereby ultrafast processes on the attosecond scale can be measured and controlled. This involves, on the one hand, the generation of attosecond pulses in a wide wavelength range of the visible spectrum: from infrared light through to hard X-rays. On the other hand, the researchers want to increase the intensity of the pulses and shorten them further in order to be able to not only observe electronic processes, but control them as well.
Another aim of the scientists collaborating in the Max Planck Center is to use the expanded experimental capabilities to investigate how exactly the chemical reactions proceed and the effects in solid bodies, such as superconductivity, which are based on the interplay of many electrons, for example. Moreover, they study molecular processes which are crucial for the effects of medicinal active agents. A more refined attosecond technology would also make it possible to monitor the motion of the electrons close to the atomic nucleus or even processes in the atomic nucleus itself, such as radioactive decay, in real time. In addition, ultrashort, intense pulses will allow researchers to analyse biomolecules, whose structure cannot be clarified with the conventional methods.
Ultimately, the researchers are intervening in processes which last only a few attoseconds: they thus want to force chemical reactions which can follow different paths into the desired direction in each case by directing the electrons appropriately during the process. Attosecond pulses also make it possible to control the behaviour of the electrons in solid bodies and hence the concomitant properties of a material. The researchers at the Max Planck Center are therefore laying the foundations for electronics which no longer operate with the microwave frequency of a few gigahertz, but with the frequency of light, which is on the terahertz scale, and thus enables arithmetic operations to be up to 10,000 times faster than current processors allow.
Picture: Research iinfrastructure at Pohang University of Science & Technology. © dpa/MPG