Scientists in Finland have just measured one of the tiniest amounts of energy ever recorded — and the breakthrough could change how engineers build quantum computers and how astronomers hunt for dark matter.
A team led by Academy Professor Mikko Möttönen at Aalto University, in collaboration with quantum computing company IQM and the Technical Research Centre of Finland (VTT), used an ultra-sensitive calorimeter to detect an electromagnetic pulse carrying just 0.83 zeptojoules of energy. A zeptojoule is one trillionth of one billionth of a joule. For comparison, it is roughly the amount of work needed to lift a single red blood cell a nanometre upward against Earth''s gravity.
The team''s study was published in Nature Electronics, and it represents an unprecedented leap in energy sensitivity. The device''s energy resolution came in at finer than 0.95 zeptojoules, corresponding to about 170 photons at 8.4 gigahertz — a level of precision that opens the door to entirely new kinds of measurements.
So how do you measure something that small? The trick lies in superconductivity. The Aalto team built a sensor combining two kinds of metals: superconducting materials, where electrical current flows without resistance, and ordinary conductors that produce resistance. When a tiny microwave pulse arrives, it deposits its energy in the structure and warms it ever so slightly. That warming is enough to disrupt the superconducting state — and that disruption is what the sensor reads.
"That combination of metals makes superconductivity such a fragile phenomenon that it weakens immediately if the temperature in the ultracold conductor rises even a little bit," Möttönen said. "This makes it such a sensitive setup." Möttönen, who also co-founded the European quantum computing unicorn IQM, has spent years building tools at the edge of what physics allows.
After running the microwave pulse through the device and applying optimized filtering, the team read out the result: an electromagnetic pulse so small it almost defies belief. The fact that they could measure it accurately is a milestone in itself.
The applications are significant. Quantum computers operate by manipulating individual photons and qubits, and the cleaner you can read out a quantum state, the more reliable and scalable a quantum computer becomes. A sensor that approaches the sensitivity needed to count individual photons would be a powerful new tool in that effort. The Aalto team has not yet reached single-photon counting, but they have closed much of the gap.
Beyond quantum computing, the technology has major implications for fundamental physics. Dark matter — the mysterious substance thought to make up about 85% of the matter in the universe — has never been directly detected. One leading candidate, the axion, is predicted to interact with electromagnetic fields in extremely faint ways. Spotting such a signal requires sensors that can see vanishingly small energies. Tools like the one developed at Aalto could help dark matter experiments push deeper into previously inaccessible parameter spaces.
The research also has potential applications in radio astronomy, where ultra-faint signals from distant cosmic sources are routinely lost in instrument noise. A more sensitive front-end detector could let radio telescopes see further and capture phenomena that current technology misses.
The work builds on decades of advances in cryogenic engineering. To keep the sensor stable, the researchers cooled their setup to temperatures close to absolute zero — colder than the depths of outer space. At those temperatures, the strange rules of quantum mechanics dominate, and tools like this one can begin to probe the universe at its most fundamental scales.
Finland has emerged as one of Europe''s leading quantum hubs, with Aalto University, VTT, and IQM forming a tight ecosystem of academic and industrial expertise. This latest result reinforces that reputation — and gives the rest of the world a powerful new instrument to start measuring just how small "small" can really get.
