One molecule, one photon: Entanglement makes an imperceptible recoil measurable
For decades, light has been used to understand the molecular structures of matter. A sample is irradiated with light, and measurements determine the wavelengths at which it is absorbed. Since each molecule absorbs light at very specific wavelengths that depend on its structure, the resulting absorption spectrum acts like a molecular fingerprint. For individual molecules, however, this signal is…
A team led by Philipp Schindler from the University of Innsbruck's Department of Experimental Physics has successfully measured the spectrum of a single calcium hydroxide molecule using quantum logic spectroscopy. This technique involves coupling two ions via their electric repulsion, with one ion being a molecular ion and the other an easily controllable auxiliary atom.
By using a quantum-mechanically entangled atom as a detector, the researchers were able to detect the minute recoil caused when a single infrared photon is absorbed by the molecule. This recoil is typically too small to be detected directly, but the entanglement of particles in a Schrödinger's cat state greatly enhances the sensitivity of the system.
The study identified a characteristic molecular vibration, the O-H stretching vibration, of the singly charged calcium hydroxide molecular ion, and the measured spectrum matched theoretical calculations from collaborators at the University of Warsaw. The method is nondestructive, allowing for precise spectroscopy of complex molecules and various applications in future quantum technologies.
Written by urgent.news from Phys.org's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
