Sculpted light steers attosecond electron bursts in a tunnelling microscope

Overview

Updated 1 hour ago

For four decades, the scanning tunnelling microscope has read a steady trickle of current, resolving atoms but saying nothing about how electrons move at their natural timescale. A team at the Technion–Israel Institute of Technology, working with theorists in Germany, France and Spain, has now fired bursts of tunnelling current through an STM junction lasting 860 attoseconds — and steered which direction they flow, using only the shape of a two-colour laser pulse. An attosecond is a billionth of a billionth of a second.

The result, published in Nature Photonics, rests on two-colour waveform synthesis: overlapping a laser's fundamental frequency with its second harmonic creates an asymmetric field that tilts the tunnel barrier and fixes the instant within each optical cycle when tunnelling is most probable. Adjusting the relative phase flips that instant — and with it the current's direction. The setup runs at room temperature in air, holds 2 nm lateral resolution and sub-angström vertical sensitivity, and works through a three-step transport process in the non-adiabatic tunnelling regime. That combination is new: atomic-scale positioning plus sub-femtosecond timing in a single probe, aimed at triggering and imaging ultrafast charge dynamics at chosen sites on a surface.

Why it matters

A microscope that can launch and image electron motion at a chosen atom could watch charge transfer in molecular junctions and solar materials as it happens, not just infer it after the fact.

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Key Indicators

860 attoseconds

Duration of each tunnelling current burst

Theory-derived duration of the current pulse, under a single femtosecond.

2 nm

Lateral spatial resolution

The laser-driven current remains a genuinely microscopic probe across the junction.

Sub-angström

Vertical topographic sensitivity

The driven current responds to height changes at the level of individual atoms.

2 colours

Laser fields combined for waveform control

Fundamental frequency plus second harmonic generate the asymmetric field that steers the current.

Voices

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Organizations Involved

Technion–Israel Institute of Technology

Research university

Lead institution behind the experiment

Israel's oldest technical university, founded in 1912, and home to the experimental team behind the attosecond STM result.

Nature Photonics

Peer-reviewed scientific journal

Publisher of the research paper

A leading journal covering optics and photonics, where the team published its findings.

Timeline

1981 October 2026

4 events Latest: Yesterday

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October 2026
Attosecond current control reported in a scanning tunnelling microscope
Latest Publication

Technion team and European theorists report steering tunnelling current with two-colour laser pulses in Nature Photonics, with a theory-derived burst duration of 860 attoseconds, 2 nm lateral resolution, and sub-angström vertical sensitivity under ambient conditions.
Yesterday
2024
Attomicroscopy demonstrated in transmission electron microscope
Milestone

A University of Arizona-led team achieves attosecond temporal resolution in a transmission electron microscope, imaging field-driven electron dynamics in graphene.
2024
2001
First attosecond pulses generated
Milestone

Attosecond spectroscopy emerges, tracing electron dynamics in time but without spatial localization. The work later earns the 2023 Nobel Prize in Physics.
2001
1981
Scanning tunnelling microscope invented
Invention

Gerd Binnig and Heinrich Rohrer at IBM Zürich build the first STM, earning the 1986 Nobel Prize in Physics. It resolves individual atoms but reads steady, time-averaged current.
1981

Scenarios

Attosecond STM images charge dynamics in a single molecule

Possible Resolves by Oct 22, 2028

Discussed by: The Technion team and collaborators, who state this goal in the paper

The team extends the waveform-controlled STM to trigger and image ultrafast charge transfer at a specific site — a single molecule, a defect, or a molecular junction. A follow-up study showing electron motion resolved in both real space and real time would validate the technique's core promise.

Independent labs reproduce and extend the technique

Possible Resolves by Oct 22, 2029

Discussed by: The broader attosecond and microscopy communities

Other groups adopt two-colour waveform synthesis in their own STM junctions, extending it to cryogenic vacuum or to different materials. Independent replication would mark the method as a general tool rather than a single-lab feat.

Ambient-condition limits stall broader adoption

Unlikely Resolves by Oct 22, 2028

Discussed by: Skeptics noting the difficulty of the measurement

Thermal artefacts and environmental noise — the obstacles the team had to work around — prove too hard for other groups to manage reliably. The demonstration stands as a single result without a follow-up wave of applications.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

2001

First attosecond pulses (2001)

A group led by Ferenc Krausz at TU Vienna generated pulses under a femtosecond, opening the attosecond regime — the natural timescale of electron motion. Attosecond spectroscopy became the standard way to trace how electrons respond to light fields in time.

Then

Researchers could time electron dynamics with sub-femtosecond precision, but measurements were ensemble averages without spatial localization.

Now

The field earned the 2023 Nobel Prize in Physics and established lightwave electronics, where the carrier wave of light itself gates electronic processes.

Why this matters now

This new STM result attaches that temporal precision to a scanning probe, adding the atomic-scale spatial resolution attosecond spectroscopy never had.

2024

Attomicroscopy (2024)

A University of Arizona-led team achieved attosecond temporal resolution in a transmission electron microscope by gating a single electron pulse, then measured field-driven electron dynamics in multilayer graphene using attosecond electron diffraction.

Then

The demonstration, coined 'attomicroscopy,' showed electron motion can be imaged in real time and space for the first time.

Now

It opened the door to attosecond imaging of quantum and complex systems, connecting electron dynamics to structural dynamics.

Why this matters now

The Technion result is complementary: attomicroscopy images through a transmitted beam, while the STM approach positions the probe on a specific surface site, in principle imaging localized charge dynamics at a chosen molecule or defect.

1981

Invention of the scanning tunnelling microscope (1981)

Gerd Binnig and Heinrich Rohrer at IBM Zürich built the first STM, which measures the quantum tunnelling current between a sharp metal tip and a surface. It resolved individual atoms and later nudged single atoms into place, earning the 1986 Nobel Prize in Physics.

Then

The STM became the gold standard for atomic-resolution imaging of surfaces.

Now

Its steady, time-averaged current proved a fundamental limit — the instrument could not see electrons move on their natural attosecond timescale.

Why this matters now

The new work breaks that limit by gating tunnelling with the sub-cycle waveform of light, giving the STM a timing resolution it has lacked since its invention.