In laboratories in Germany, electrons in graphene suddenly jump across forbidden energy gaps, and with a probability of up to one hundred percent. This is not a measurement error but a real process that has been captured in real time.
A team of scientists from the University of Regensburg, the Philipps University of Marburg and the Jülich Research Centre conducted an experiment published in the journal Nature on 2 November 2026. They used a photoemission pulse microscope combined with powerful laser pulses to track the motion of electrons in atomically thin layers of ultrahigh-purity graphene grown in Jülich. The method has been called subcycle videography: it makes it possible to capture events occurring within fractions of a femtosecond.
In ordinary semiconductors, electrons remain in their energy band, separated by a forbidden gap. Here, however, under the action of a strong electric field from a light pulse, electrons are accelerated and cross the gap without intermediate states. Imagine an elevator that moves instantly from the first floor to the twentieth, skipping all the others: that is exactly what the Landau-Zener-Majorana transition looks like. The velocity of electrons at the band edge determines the probability of such a jump, and in graphene it reaches one hundred percent.
The experiment showed that interaction with the crystal lattice can disrupt ordered motion, but the tunnelling itself remains predictable. This is fundamentally different from classical tunnelling through a spatial barrier — here the key role is played by dynamics in time.
The discovery opens the way to controlling electrons in two-dimensional materials with light rather than only with electrical voltages. In the future, such methods could form the basis of new devices in which quantum transitions become a working tool rather than a rare exception.
The results published in Nature confirm that the method of subcycle videography also works on other quantum materials, giving a panoramic view of their energy landscape.
