Space-Time Limit: Electron Tracking Could Speed Electronics
Researchers have experimentally observed a limit on how precisely scientists can determine both an electron’s location and its behavior over time. The finding, called the space-time limit, could inform quantum technology and ultrafast electronics, while a new laser system let the team study individual electrons at attosecond timescales.
Researchers have experimentally demonstrated a hidden limit space time places on how precisely scientists can determine an electron’s location and behavior over time, a finding that could inform ultrafast electronics and quantum technology.
The newly observed relationship, called the “space-time limit,” differs from the familiar uncertainty principle, which concerns pairs of particle properties such as position and momentum. Researchers said the restriction is built into the behavior of electrons, not caused by imperfect instruments.
Laser pulses track electron motion
An international collaboration involving research groups at the Regensburg Center for Ultrafast Nanoscopy and a team at the Max Planck Institute in Hamburg conducted the work. The Regensburg groups were led by Profs. Jascha Repp, Rupert Huber, Franz Giessibl and Klaus Richter; the Hamburg team was led by Angel Rubio.
The researchers built a laser system with finer time resolution than earlier experiments to study the quantum motion of individual electrons. Carefully timed laser pulses drove electrons from an extremely sharp metal tip toward a silver surface, across a distance of only a few atomic diameters.
To track the movement, the team measured the resulting electrical current and varied the interval between two light pulses. “By varying the time interval between the two laser pulses, we can directly observe how the electrons respond,” said Simon Maier, the paper’s lead author.
The approach revealed electron motion on attosecond timescales. An attosecond is one-billionth of a billionth of a second. The researchers said the pulses could transfer electrons within these brief intervals.
Why the limit matters
Understanding how electrons move through materials can help researchers investigate processes relevant to clean energy, quantum computing and electronics used for artificial intelligence, the team said. Scientists need to observe both where particles are and how their behavior changes over time to build a fuller picture of events at the atomic scale.
Researchers at the Regensburg center are developing ultrafast microscopes to record the movement of electrons, atoms and molecules in space and time. About ten years ago, scientists there used ultrafast scanning tunneling microscopy to resolve a single molecule’s movement across space and time for the first time.
Electrons are harder to track because they can move roughly a thousand times faster than atoms and molecules, with important changes occurring over just attoseconds. An atom is approximately ten million times smaller than a millimeter, the research account said.
