Leiden’s Microscope Revolutionizes Quantum Chip Testing

Physicists in Leiden have developed a microscope that can assess four important features of a material in a single scan, all with nanoscale precision. The device can even evaluate complete quantum chips, which will speed up research and innovation in quantum materials. The results were reported in the journal Nano Letters.

This revolutionary microscope exposes material characteristics such as temperature, magnetism, structure, and electrical properties.

It almost feels like having a superpower. You look at a sample and see not only its shape but also the electrical currents, heat, and magnetism within it.

Matthijs Rog, PhD Student, Leiden University

Kaveh Lahabi, who led the group added, “This microscope removes the experimental bottlenecks that have long limited the study of quantum materials. This is not an idealized technique – it works on the systems we actually want to understand. Furthermore, the sensitivity of our measurements tends to impress a lot of my physicist colleagues.”

Answering Fundamental Questions

Understanding the operation of quantum materials and devices is critical for next-generation technologies such as quantum computing and sensing. Because of their complexity, it remains difficult to fully understand how these materials function: their magnetic, electronic, thermal, and structural properties are tightly interconnected at extremely small scales. Because this microscope can directly visualize these features, it offers researchers a powerful way to address fundamental questions surrounding the use and behavior of quantum materials.

What Are Quantum Materials About?

Quantum materials are those whose characteristics can only be fully understood using quantum mechanics. A superconducting material, for example, is capable of transmitting electric current without resistance. Normally, quantum characteristics can only be seen at the scale of individual atoms or a few nanometers; quantum materials already function quantum mechanically at the millimeter scale.

No one fully understands why, largely because these systems are so intricate. The material contains billions of particles, each behaving in a distinctly quantum manner.

Such complexity is very hard to capture in a theory. A lot of things come together at the smallest scales. It is therefore very nice that we can use this microscope to simply look for ourselves how these materials behave, and why they do what they do.

Matthijs Rog, PhD Student, Leiden University

“Whatever quantum material we place under this microscope in the coming years, I’m certain we’ll discover something new,” Rog predicted.

This is an unprecedented way to explore materials.

Rog added, “Until a few months ago, our experiments were mainly about proving that the microscope worked. Now we can start tackling the real puzzles: materials we genuinely find interesting. We can’t wait.”

From Flat Crystals to Uneven Quantum Chips

“Most existing microscopes only work well with very flat samples. That’s limiting, because many of the most interesting effects occur at the edges of materials or at the boundary between two different quantum materials. Our microscope has no trouble with that at all – it can examine a bumpy chip just as easily as a flat crystal,” Rog further added.

Designed and Built Together with Instrument Makers

Since 2021, Rog and Lahabi have been working on the creation of this new microscope, affectionately known as ‘Tortilla’ by the team. The technical term is ‘Tapping Mode SQUID-on-Tip’ (TM-SOT).

The project began with components discovered in the university’s attic, supplemented by a handful of commercially available microscope parts. However, it soon became clear that the design requirements were so exacting that the team had to develop and manufacture nearly every component in-house.

Rog and Lahabi enlisted the assistance of Christiaan Pen and Peter van Veldhuizen, both from the Fine Mechanical Service and the Electronic Service. They worked together to develop and build every component of the microscope.

“Every cable was soldered by us, and every screw was put in by hand. This project is a result of intense and fruitful collaboration between many different scientists, engineers and technicians. Microscopy experts from the group of Milan Allan and the talented engineers of QuantaMap all played a vital role,” Rog noted.

Start-Up QuantaMap Brings the Microscope to Market

The same microscope is currently being developed as a product by QuantaMap, a company located at the House of Quantum Leiden and co-founded by Lahabi.

We see strong potential in quantum diagnostics. We concluded that one of the major road-blocks of quantum computing is that when chips do not work as well as they should (they often don’t), there is no way to find out which component failed. Nor how to improve the production process. Our novel microscope can solve this diagnostic challenge and help enable the quantum revolution.

Johannes Jobst, Chief Executive Officer, QuantaMap