Upgraded Microscope Tracks Single Quantum Particles Moving Through Materials

"That's always been the catch," Delor said. "To take single-particle measurements, you need to start with a low density of carriers, but, as they move, they become lost in the noise of the measurements."

How did the team break the single-particle barrier?

The solution came from outside Columbia. A few years ago, researchers at the University of Würzburg and the University of Ottawa published a technique for distinguishing single quantum particles by taking spectroscopic measurements at varying laser intensities. Spectroscopy measures how light interacts with matter, but it doesn't capture spatial information — where particles are inside a material.

Delor's team realized their microscope was well suited to a similar tweak: cycling different intensities of light to create the excitations, while keeping the spatial imaging stroboSCAT already provided.

"It's an elegant solution to a major obstacle: We can now distinguish single quantum states from many as they move through real space," Delor said.

What can the new instrument actually do?

In the Nature Materials paper, Tulyag and colleagues demonstrated several capabilities. The headline result, for Delor, is isolating single electrons moving through a 2D semiconductor — a material only one atomic layer thick.

"That's a breakthrough for me. We can obtain information about transport without worrying about artifacts from many-body interactions," he said, referring to the distorting effects that crowds of particles have on each other's behavior.

Beyond single particles, the technique also lets the team watch interactions among multiple particles with unusual precision. In the paper, they:

• selectively track the spatial and temporal evolution of two-particle and three-particle states;
• detail interactions between individual excitons;
• map how crystal defects shape a 2D semiconductor's electronic environment;
• observe how light can force a phase transition in a superatomic solid.

"These are long-sought-after capabilities that can now become routine measurements," Delor said. He's not keeping the instrument to himself: he's making stroboSCAT's blueprints and software available and helping interested groups build their own.

What comes next?

At Columbia, Delor plans to point the upgraded microscope at particle interactions behind some of physics' most intriguing phenomena. Two targets stand out: Cooper pairs — bound electron pairs that give rise to superconductivity, the flow of electricity without resistance — and condensates, in which many quasiparticles synchronize into a shared, macroscopic quantum state.

He won't lack for materials to study. Columbia colleagues are already keen to bring their own quantum materials under the microscope.

"What's amazing about stroboSCAT is it's such a general technique," Delor said. "It's remarkable that we can track all these different particles in many different materials and now, with single-particle precision."

Where was it published?

The findings appear as Jakhangirkhodja A. Tulyagankhodjaev et al., "Spatiotemporal intensity-cycling microscopy unveils many-body interactions and correlated transport in van der Waals semiconductors," Nature Materials (2026), DOI: 10.1038/s41563-026-02800-6. A companion piece, Pavel Malý's "Imaging multi-particle dynamics in space and time," appears in the same journal (DOI: 10.1038/s41563-026-02785-2).

As with any newly demonstrated technique, broader adoption will depend on other labs replicating the results — something Delor's open blueprints are designed to encourage. But if the method spreads as planned, measurements that once required bespoke effort could become standard practice for studying how energy moves through the materials of future electronics.