# Regensburg and Max Planck teams measure a space-time limit for electrons on an attosecond scale

- Published: 2026-11-08 17:35 UTC
- Section: Science › Physics
- Tags: electron space-time limit, attosecond electron motion, quantum tunneling experiment, electron wave packet, Max Planck Institute Hamburg, Ángel Rubio simulations, ultrafast laser pulses, peak current density
- URL: https://realtech.media/news/rt-ac68e583001fd6d8a6231511_regensburg_and_max/

**A laser experiment with a metal tip resolved electron tunneling on attosecond scales and showed that finer timing stretches the electron wave packet in space.**

![Regensburg and Max Planck teams measure a space-time limit for electrons on an attosecond scale](https://realtech.media/media/2026/11/8f8b3294bf10c41d.webp)
*ua.news*

An international group of researchers has experimentally demonstrated a fundamental limit to the precision with which an electron's position and the time of its motion can be determined simultaneously, ua.news reports. The work involved groups from the Regensburg Center for Ultrafast Nanoscopy and the Max Planck Institute in Hamburg. [1]

## Attosecond laser experiment

To observe the quantum motion of electrons, the researchers built a laser system with high temporal resolution. Precisely synchronized laser pulses directed electrons from an ultrasharp metal tip toward a silver surface separated from it by several atomic diameters. [1]

The motion was recorded as electric current, while the transfer time was determined with two light pulses at a controlled interval. The electrons crossed the energy barrier by quantum tunneling, behaving as quantum waves rather than ordinary particles. The measurements showed motion on attosecond time scales; an attosecond is one billionth of one billionth of a second. [1]

Quantum simulations by the team led by Ángel Rubio reproduced the experimental results. They also showed that the electrons responded to the light field with a delay of about 500 attoseconds. [1]

## Timing precision and the wave packet

The scientists found that the more precisely they tried to determine the time of an electron's motion, the more energy had to be supplied to the system. As a result, the electron's wave packet, which describes its spatial extent in quantum mechanics, stretches in space. [1]

To verify this relationship, the researchers placed a single atom on the surface, which confined the wave packets before the laser pulses arrived. [1]

The authors believe that controlled electron wave packets could eventually help initiate chemical reactions and observe changes in chemical bonds. According to the researchers, concentrating a single electron in an extremely small space over an extremely short period can create a local peak current density of up to 1 trillion amperes per square centimeter. [1]

The scientists also view the results as a basis for future electronic devices and quantum information-processing systems that would operate closer to the fundamental speed limit of electron motion. The authors describe electronics hundreds of thousands of times faster than current CMOS technology as a long-term goal, not a result of the present experiment. [1]

## Sources

1. [ua.news](https://ua.news/en/dovkolo-svitu/doslidniki-pokazali-prostorovo-chasove-obmezhennia-dlia-elektroniv-sciencedaily)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-ac68e583001fd6d8a6231511_regensburg_and_max/