Researchers have developed a new quantum-based sensor that can detect extremely tiny molecular vibrations by using virtual particles—fleeting photons that constantly appear and disappear due to quantum uncertainty. Traditional methods like infrared and Raman spectroscopy often struggle because the interaction between light and molecules is weak, producing faint signals that are easily lost in noise. To overcome this, the researchers built tiny optical cavities using highly reflective gold mirrors. Inside these cavities, virtual photons bounce rapidly and strongly interact with the vibrations of molecules placed inside. This interaction creates a hybrid quantum state called a vibropolariton, which mixes light and molecular motion. By analyzing these vibropolaritons with infrared light, the sensor can identify molecules with far greater sensitivity than classical optical methods. In experiments, the device successfully detected the molecule 4-mercaptobenzonitrile under normal room conditions—no vacuum or extreme cooling needed. This shows that fragile quantum effects can now be used in practical, everyday environments. The researchers envision future applications such as early medical diagnostics, real-time monitoring during drug production, and environmental sensors that can detect hazardous chemicals at extremely low levels. Their findings were published on 15 August in Science Advances.
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