Watching Rydberg Molecules Vibrate in Slow Motion

Physics 16, s7
Researchers have recorded for the first time the dynamics of vibrating Rydberg molecules, the slow-motion counterparts of regular molecules.
K. Ureña-Alvarado

The molecular vibrations in liquids and gases determine properties such as their capacity to absorb heat and their chemical reactivity. However, the small size of most molecules means that these vibrations are often too fast to be accurately analyzed. Now Yi-Quan Zou and collaborators at the University of Stuttgart, Germany, have found a workaround: instead of measuring the vibrations of conventional molecules, they consider giant “Rydberg molecules” [1]. The enormous size of such molecules—comparable to the size of bacteria—leads to slower vibrations that can be manipulated with weak electric fields, facilitating a controlled analysis.

Zou and colleagues start with a cloud of rubidium atoms at 20 µK. Using two pairs of lasers, they ionize one atom and excite a second atom to a Rydberg state—a state in which an electron occupies a high-energy level. The ion and the Rydberg atom naturally bond, forming a Rydberg molecule. Such ion-Rydberg-atom molecules are especially susceptible to external electric fields due to their huge dipole moment (1000 times larger than the water-molecule dipole moment), which Zou and colleagues use to control the molecular vibrations. After triggering such vibrations, they measure the positions of the ion and the Rydberg atom with an accuracy and a resolution that have not been achieved for the much more rapidly oscillating atoms in a normal molecule.

The researchers say that their method can be extended to study more complicated dynamic processes in molecules, such as interactions with light. Additionally, direct tracking of atomic motions within molecules during chemical reactions could help devise strategies to control such reactions at the quantum level.

–Martin Rodriguez-Vega

Martin Rodriguez-Vega is an Associate Editor for Physical Review Letters.


  1. Y. Q. Zou et al., “Observation of vibrational dynamics of orientated Rydberg-atom-ion molecules,” Phys. Rev. Lett. 130, 023002 (2023).

Subject Areas

Atomic and Molecular Physics

Related Articles

<i>Nobel Prize</i><i>:</i> Flashes of Light Catch Electrons in the Act

Nobel Prize: Flashes of Light Catch Electrons in the Act

The 2023 Nobel Prize in Physics honors the field of attosecond physics, which offers a nonblurry view of the fast-moving electrons around atoms and molecules. Read More »

Quantum Ratchet Made Using an Optical Lattice
Atomic and Molecular Physics

Quantum Ratchet Made Using an Optical Lattice

Researchers have turned an optical lattice into a ratchet that moves atoms from one site to the next.  Read More »

Milestone for Optical-Lattice Quantum Computer
Atomic and Molecular Physics

Milestone for Optical-Lattice Quantum Computer

Quantum mechanically entangled groups of eight and ten ultracold atoms provide a critical demonstration for optical-lattice-based quantum processing. Read More »

More Articles