Attophysics — new tools to fathom the world of electrons

Subject : Science and tech

Section: Awards

Context:

On October 3, the 2023 Nobel Prize for physics was awarded to Anne L’Huillier, Pierre Agostini, and Ferenc Krausz “for experimental methods that generate attosecond pulses of light for the study of electron dynamics in matter”.

What is attosecond science?

Attosecond science, including attosecond physics, or attophysics, deals with the production of extremely short light pulses and using them to study superfast processes.

Why in news?

The Nobel Prize in Physics for 2023 has gone to three scientists – Anne L’Huillier, Pierre Agostini, and Ferenc Krausz.
The work of these scientists made it easier to observe electrons and has potential applications in the field of diagnosing diseases and developing electronic gadgets.

Electrons move so fast that it is impossible to observe them in real time.

These three scientists produced pulses of light that last only attoseconds, which is 1×10⁻¹⁸ of a second.
The short pulses of light thus produced can be used to measure the rapid processes in which electrons move or change energy.

How do we know a pulse lasts for an attosecond?

A major technique to measure the duration of a short light pulse is called RABBIT — and Pierre Agostini and his colleagues developed it in 1994.
Here, the attosecond pulse and another pulse of a longer duration are shined on atoms of a noble gas.
Due to the photoelectric effect, the photons in the two pulses kick out electrons from the atoms. Physicists harvest data about these electrons and the atoms.
The principles of producing and then measuring attosecond pulses were finally in place.
In 2001 Agostini et al., in Paris, and Ferenc Krausz et al. in Vienna were able to produce verified attosecond pulses in a ‘train’: a pulse followed by a gap, followed by a pulse, and so forth.
The pulse duration in the former case was 250 as. In the latter, the Krausz group produced a pulse train with a pulse duration of 650 as, and using a filtering technique was also able to isolate a single pulse, a bullet of light.
By 2017, experts were able to produce a pulse as short as 43 attoseconds.
The current world record for the shortest light-pulse generated by human technology is 43 as.

The main interests of attosecond physics are:

Atomic physics: investigation of electron correlation effects, photo-emission delay and ionization tunneling.
Molecular physics and molecular chemistry: role of electronic motion in molecular excited states (e.g. charge-transfer processes), light-induced photo-fragmentation, and light-induced electron transfer processes.
Solid-state physics: investigation of exciton dynamics in advanced 2D materials, petahertz charge carrier motion in solids, spin dynamics in ferromagnetic materials.
One of the primary goals of attosecond science is to provide advanced insights into the quantum dynamics of electrons in atoms, molecules and solids with the long-term challenge of achieving real-time control of the electron motion in matter.

Source: TH