Coherent and Incoherent Light Scattering by Single-Atom Wave Packets
A single-atom, single-photon scattering experiment shows you can probe which-way information and coherence in free space without “trap-specific” effects being the deciding factor.
Published on: Jul 22, 2025
Researchers study how single photons scatter from single-atom wave packets in free space, framing results in terms of atom–photon entanglement and which-way information. Using ultracold atoms released from an optical lattice, they implement a thought-experiment-style interference test, then compare scattering before vs. during wave-packet expansion. They find the coherence properties of the scattered light don’t depend on whether a trap is present, and argue several “trap-specific” effects aren’t essential to the coherent vs. incoherent scattering question—highlighting atomic Mott insulators as a platform for precision fundamental tests.
DOI: 10.1103/zwhd-1k2t
Key Takeaways
Coherence vs. incoherence in light scattering is fundamentally about information/entanglement—not whether the atom is trapped.
Demonstrates a clean, controllable platform for quantum measurement / which-way questions using ultracold atoms.
Unifies “trapped atom” and “free-space wave packet” pictures by directly measuring scattering across wave-packet expansion.
Positions atomic Mott insulators as a practical source of high-quality single-atom wave packets for foundational experiments.
Institutions
Massachusetts Institute of Technology (MIT)
Cambridge, Massachusetts, United States
MIT Research Laboratory of Electronics (RLE)
Cambridge, Massachusetts, United States
MIT–Harvard Center for Ultracold Atoms
Cambridge, Massachusetts, United States
Journal
American Physical Society (APS)
