Finnish Researchers Detect Zeptojoule Energy, Advancing Quantum Sensors
Researchers in Finland have detected an amount of energy smaller than one zeptojoule, a measurement less than a trillionth of a billionth of a joule. This advance in ultra-sensitive measurement technology could improve quantum computing, assist in the search for dark matter, and eventually allow for the counting of individual photons.
The breakthrough was achieved by a team led by Academy Professor Mikko Möttönen at Aalto University, collaborating with quantum computing firm IQM and the Technical Research Centre of Finland (VTT). Their findings appeared in the journalNature Electronics. A zeptojoule represents an exceptionally small quantity of energy, roughly equivalent to the work needed to lift a red blood cell one nanometer against Earth's gravity.
Quantum Sensor Breakthrough
To reach this level of sensitivity, the researchers employed a calorimeter, a device specifically designed to measure minute changes in heat energy. Measuring such tiny signals proves significantly more complex than simply directing a beam into a detector.
Scientists directed a microwave pulse into a sensor constructed from two types of metals. One section incorporated superconductors, materials allowing electricity to flow without resistance. The other section used normal conductors, which impede electrical flow. "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. This makes it such a sensitive setup," Möttönen, a founder of IQM, explained. After careful signal filtering, the team confirmed detecting an electromagnetic pulse measuring 0.83 zeptojoules. This marks the first time a calorimetric measurement device has achieved such sensitivity, according to the researchers.
Implications for Dark Matter and Quantum Computing
To reach this level of sensitivity, the researchers employed a calorimeter, a device specifically designed to measure minute changes in heat energy.
This advance could eventually enable scientists to count individual photons, a long-standing objective in quantum technology and astrophysics. "We want to make this setup capable of measuring input that has an arbitrary time of arrival, which is important for things like detecting dark-matter axions in space when you have no idea when they might reach your system," Möttönen said.
The technology could also prove useful in quantum computers.
The calorimeter operates at the same extremely cold millikelvin temperatures required by qubits, the basic units of quantum information. Möttönen noted the device could become a component for reading out qubits in quantum computers, introducing less disturbance into the system. OtaNano, Finland's national research infrastructure for nano-, micro-, and quantum technologies, hosted the work. Funding for the project came primarily from the Future Makers initiative, supported by the Jane and Aatos Erkko Foundation and the Technology Industries of Finland Centennial Foundation.
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