Ultrafast scanning tunneling microscopy achieves quantum mechanical space-time limit breakthrough

On July 3, 2026, a collaborative research team from the University of Regensburg (RUN) and the Max Planck Institute in Hamburg announced a groundbreaking achievement in ultrafast scanning tunneling microscopy. They have successfully reached the quantum mechanical space-time limit, enabling unprecedented observation of electron motion.

Understanding the Quantum Mechanical Space-Time Limit

Werner Heisenberg's uncertainty principle has long defined the limitations of measuring certain physical quantities of particles. However, this new research reveals that the location and time evolution of an electron cannot be measured with arbitrary precision simultaneously, introducing the concept of a space-time limit.

This discovery is pivotal for future technological advancements in sectors such as green tech, quantum technologies, and high-performance electronics, which necessitate a detailed understanding of microscopic matter behavior.

Advancements in Ultrafast Microscopy

At the Regensburg Center for Ultrafast Nanoscopy, researchers have developed advanced microscopes that capture the motion of electrons, atoms, and molecules in slow-motion movies with high spatial and temporal resolution. Ten years prior, they resolved the motion of a single molecule in space and time, and now they have taken it a step further by capturing electron dynamics on attosecond timescales.

To achieve this, the team created a new laser system that controls electron motion on extreme time scales. This innovation allows for the observation of electrons transferring from an atomic metal tip to a silver surface over a distance of just a few atomic diameters.

Significance of the Findings

Lead author Simon Maier stated, "By varying the time interval between the two laser pulses, we can directly observe how the electrons respond." The results revealed that electron motion occurs on attosecond timescales, showcasing their behavior as quantum mechanical waves rather than classical particles.

The research demonstrates that electrons can tunnel through energy barriers, a phenomenon that contradicts classical physics. This tunneling effect allows researchers to visualize the process in real-time, akin to using a high-speed camera for electron wave packets.

Further simulations conducted by Prof. Angel Rubio's group provided insights into the microscopic electron dynamics at the space-time limit, illustrating that electron responses are delayed by 500 attoseconds. This research opens new avenues for exploring the fundamental limits of quantum physics.