Ultrafast scanning tunneling microscopy reaches the quantum mechanical space-time limit for the first time

Werner Heisenberg's famous uncertainty principle describes one of the most intriguing features of quantum physics: certain pairs of physical quantities describing a particle, such as position and momentum, cannot simultaneously be. The science-journalism coverage adds useful context, while the strongest evidential footing still comes from the underlying data, papers or institutional documentation.

The significance lies in physics only takes a result seriously when the measurement chain remains robust under scrutiny. Experimental particle physics and precision metrology both operate in regimes where the signal sits far below the background noise, and where systematic uncertainties can mimic new physics if not controlled rigorously. The history of the field contains numerous anomalies that generated theoretical excitement before better data showed them to be artifacts, and it also contains genuine discoveries that were initially dismissed as noise. The difference is almost always resolved by independent replication with different instruments and different systematics. This article has been reviewed according to Science X's editorial process and policies. Jascha Repp, Rupert Huber, Franz Giessibl, and Klaus Richter, as well as a team from the Max Planck Institute in Hamburg led by Angel Rubio, has now observed for the first time.

The work is published in the journal Nature Photonics. Ten years ago in Regensburg, the motion of a single molecule in space and time was resolved for the first time using ultrafast scanning tunneling microscopy.

These electron movements are measured as current, and the temporal information is obtained by using two pulses of light. Discover the latest in science, tech, and space with over 100, 000 subscribers who rely on Phys. org for daily insights.

The calculations explain the experimental results with remarkable accuracy. They also show that the electron does not follow the light field immediately, but with a tiny delay of 500 attoseconds.

The broader interest lies as much in the method as in the headline number, because a durable measurement procedure can travel farther than a single result. When experimental physicists develop a technique that achieves new sensitivity or controls a previously uncharacterized systematic, that methodological contribution persists even if the specific measurement is later revised. This is one reason why precision physics experiments often generate long-term value that is not immediately visible in the original publication.

With this latest breakthrough, the team is pushing the boundaries of a previously only vaguely suspected spatiotemporal limit of quantum mechanical electron wave functions, in. However, if the electron is confined to a tiny space-time volume, this corresponds to extremely high local peak current densities of up to 1 trillion amperes per square centimeter.

Because this item comes through Phys. org Physics as science journalism, it should be treated as contextual reporting rather than primary evidence. Good science reporting can identify why a result matters, connect it to the wider literature and make technical work readable, but the decisive evidence remains in the original paper, dataset, mission release or technical record. That distinction is especially important when a story is later repeated by aggregators, because repetition increases visibility, not evidential strength.

The next step is more measurement, tighter systematic control and scrutiny from groups whose experimental setups are genuinely independent. In experimental particle physics and precision metrology, the threshold for a discovery claim is a five-sigma excess surviving multiple analyses; an intriguing signal at lower significance is a reason to run more experiments, not a reason to revise the textbooks. Next-generation experiments currently under construction or commissioning will revisit several of the open questions that give the current result its context.

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