A team of scientists in Finland has detected an energy pulse smaller than a zeptojoule, less than a trillionth of a billionth of a joule. That is roughly the energy needed to lift a single red blood cell by one nanometer in Earth's gravity. The measurement is one of the tiniest energy signals ever recorded.
A sensor built from two kinds of metal
The device is a calorimeter, an instrument that measures tiny changes in heat. Researchers at Aalto University, together with the quantum computing company IQM and the Technical Research Centre of Finland (VTT), built the sensor from a combination of superconductors and normal conductors. Superconductors allow electricity to flow without resistance. Normal conductors resist it. That mix makes superconductivity fragile. Even a slight rise in temperature weakens it immediately. The team sent a microwave pulse into the sensor and carefully filtered the signal. They confirmed they had detected an electromagnetic pulse of 0.83 zeptojoules. According to the researchers, this is the first time a calorimetric device has reached such sensitivity.
Why this matters for quantum computers and dark matter
The advance could eventually allow scientists to count individual photons, a long-standing goal in quantum technology and astrophysics. Photons are the particles that carry light, and counting them one by one would give researchers a new level of control over quantum systems. The same precision could help improve quantum computers, which rely on manipulating tiny energy states. The sensor might also help detect dark matter particles from space. The team wants to make the setup capable of measuring signals that arrive at any time, which is important for detecting dark matter axions.
What comes next
The research was led by Academy Professor Mikko Möttönen at Aalto University. The findings were published in the journal Nature Electronics. The sensor operates at ultracold temperatures and relies on the fragile nature of superconductivity. The team says the next step is to make the detector work with arbitrary input timing. That would open the door to practical applications in quantum computing and the search for dark matter. For now, the sensor stands as a record in sensitivity, a tool that can measure energy at a scale that was once beyond reach.
