How 'Popcorn' Atoms Revealed a Quantum Motor ✛ ✦

Original: "Quantum-enabled active matter at the atomic scale"
arXiv:2606.24615 · 2026-06-23 · CC BY-SA 4.0 · 1 min
Scientists made atoms move like popcorn kernels in hot oil — using quantum collisions.

Physicists created a pot for quantum popcorn: a cloud of rubidium atoms, cooled to a single quantum state — colder than space. The cesium atoms tossed in, like kernels, 'popped' from internal energy upon collision. Swapping spin — a magnetic moment — released it, like steam in a kernel. Thus the cesium accelerated, bypassing the usual rise in disorder.

This quantum 'motor' operates under the rules of microthermodynamics, where particles exist in multiple states at once and exhibit duality — ideas from Einstein, Boltzmann, and Schrödinger.

Surprise: though the 'pot' is icy, the kernel-atoms jostle as if in boiling oil. Gradually the motion quiets — quantum forgetfulness sets in, but hypersensitive instruments captured every leap. In the future, such jumps could be harnessed for atom-based electronics.

The cloud's temperature (460 nK) is millions of times lower than the cosmic background, yet the cesium inside darts around with room-temperature energy — a baffling contrast.

Q = -\Delta m_f (g_{f,\mathrm{Cs}} - g_{f,\mathrm{Rb}}) \mu_B B
Delta m_f is the change in the projection of total angular momentum, g_f are the Landé factors, mu_B is the Bohr magneton, B is the magnetic field.
\sigma_{\mathrm{se}} = \frac{4\pi\beta}{k(1 + k^2|a|^2 + 2k\beta)} \propto \frac{1}{k}
As k -> 0, the cross section diverges as 1/k, but the collision frequency remains finite.
Scientists
Enrico FermiPaul DiracWolfgang PauliErwin SchrödingerPeter HiggsBryce DeWitt
Concepts
active matter quantum light matter interaction nuclear spin quantum action kinetic energy dynamic casimir effect interaction energy exchange spin neural activity orbital motion atomic cloud atom artificial atom carbon 13 ytterbium ion atomic transition proton dynamics charged particle