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Monitoring Quantum State Excitation in Massive Molecules

• Physics 15, s122

Laser experiments can monitor how the excitations of quantum states of a “buckyball” chill out after the molecule collides with different particles.

L.R. Liu/JILA; P.B. Changala/Harvard College

The habits of a molecule is decided by the interaction of its varied quantum states. Utilizing laser spectroscopy, researchers have probed these states and their dynamics for small molecules. These measurements, nevertheless, haven’t beforehand been potential for molecules containing tens of atoms, whose crowded spectra are tough to interpret. Now Lee Liu of JILA and the College of Colorado, Boulder, and colleagues have proven they’ll selectively excite the combined rotational-vibrational, or “rovibrational,” quantum states of a molecule composed of 60 carbon atoms after which measure how these states decay following molecular collisions [1]. The method opens alternatives for understanding and controlling such advanced quantum methods.

The experiments construct on earlier work that mixed frequency-comb spectroscopy and molecular cooling methods to characterize the rovibrational construction of a C60 molecule, or “buckyball.” The staff has now prolonged that work to review the molecule’s dynamics. Utilizing a delicate approach based mostly on an infrared laser coupled to an optical cavity, they excited particular person rovibrational states of a inhabitants of buckyballs in a buffer gasoline and measured the decay charges of those states after collisions between the buckyballs and the gasoline. They discovered that the decay charges dramatically relied on the gasoline kind.

Whereas the staff measured how briskly the vitality in every excited state decayed, they couldn’t measure to what different states it was transferred. The staff plans to glean that info by equipping the setup with a frequency comb that may concurrently probe many rovibrational states. Such quantum state-to-state monitoring may assist researcher refine their understanding of the many-body physics of enormous, symmetric molecules like C60, Liu says.

–Matteo Rini

Matteo Rini is the Editor of Physics Journal.


  1. L. R. Liu et al., “Collision-induced

    rovibrational rest probed by state-resolved nonlinear spectroscopy,” PRX Quantum 3, 030332 (2022).

Topic Areas

Atomic and Molecular Physics

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