Quantum Light Distinguishes Twin Molecules express
Many molecules, like amino acids, are like musical notes: their left and right versions sound almost identical, yet the difference is critical. One heals, the other is poison. Picking up this difference is hindered by inescapable noise, like in a room where a fan is loudly running. Regular spectroscopy misses the nuances.
Scientists applied a quantum trick: they squeezed the light so that the noise in one characteristic dropped sharply at the expense of others, like turning down the fan to hear a quiet ring. This method, called squeezed light, made it possible to distinguish left and right amino acids in ordinary water. Sensitivity increased by 5 decibels — akin to catching a whisper from twice the distance.
Now light measurements can check drug purity, detect diseases by molecular signatures, and even search for life on distant worlds, where the balance of mirror forms of carbon compounds will be key to the mystery.
The smell of mint and caraway comes from the same molecule, but with different chirality.
In Lewis Carroll's 'Through the Looking-Glass,' the world is a reflection of ours. Chiral molecules are like messengers from that realm, and quantum light is a detector that tears off their masks.