Quantum mechanics operates at incredibly minute scales, prompting scientists to innovate increasingly precise tools for measuring and manipulating phenomena like photons--the fundamental particles of light. Enhanced precision paves the way for more advanced quantum devices and deeper insights into some of the universe's most profound mysteries.
A zeptojoule represents an almost unfathomably small measure of energy, comparable to the work necessary to elevate a red blood cell by a mere nanometer against Earth's gravity.
This groundbreaking research was spearheaded by Academy Professor Mikko Möttönen at Aalto University, in partnership with quantum computing firm IQM and the Technical Research Centre of Finland (VTT). Their significant findings were published in the journal Nature Electronics.
Ultra-Sensitive Quantum Energy Detector
To achieve this remarkable sensitivity, the team utilized a calorimeter--a device adept at detecting minuscule variations in heat energy. Capturing signals of such diminutive scale is considerably more complex than simply directing a beam into a detector and interpreting the outcome.
The scientists directed a microwave pulse into a sensor constructed from two distinct metal types. One segment incorporated superconductors, which permit electricity to flow without resistance, while the other used conventional conductors, which inherently resist electrical flow.
"This combination of metals renders superconductivity a delicate phenomenon, susceptible to immediate weakening if the temperature of the ultracold conductor rises even slightly. This sensitivity is what makes our setup so remarkable," explains Möttönen, also a co-founder of the quantum computing start-up IQM.
After meticulous signal filtering, the researchers confirmed the detection of an electromagnetic pulse measuring just 0.83 zeptojoules, marking a historic achievement for calorimetric measurement devices.
Implications for Quantum Computing and Dark Matter
This advancement could ultimately enable scientists to count individual photons--a long-sought objective in both quantum technology and astrophysics.
"Our goal is to enhance this setup to measure inputs arriving at arbitrary times, which is crucial for detecting dark-matter axions in space, especially when their arrival is unpredictable," Möttönen added.
Furthermore, the researchers believe this technology could significantly benefit quantum computing, as the calorimeter functions at the extremely low millikelvin temperatures that qubits--the basic units of quantum information--require.
"Since a calorimeter operates within the same millikelvin temperatures as qubits, it minimizes system disturbances, allowing us to avoid heating the device or amplifying the qubit measurement signal for results. In the future, our device could serve as a vital component for reading qubits in quantum computers," Möttönen concluded.
Research Facilities and Funding
The research was conducted at OtaNano, Finland's national research infrastructure dedicated to nano-, micro-, and quantum technologies. Funding was primarily provided through the Future Makers initiative, supported by the Jane and Aatos Erkko Foundation and the Technology Industries of Finland Centennial Foundation.