Famous double-slit experiment holds up at the single atom level

Amazing stuff!

"MIT physicists have performed an idealized version of one of the most famous experiments in quantum physics. Their findings demonstrate, with atomic-level precision, the dual yet evasive nature of light. They also happen to confirm that Albert Einstein was wrong about this particular quantum scenario. ...

Scientists have since carried out multiple versions of the double-slit experiment, and they have all, to various degrees, confirmed the validity of the quantum theory formulated by Bohr. Now, MIT physicists have performed the most “idealized” version of the double-slit experiment to date. Their version strips down the experiment to its quantum essentials. They used individual atoms as slits, and used weak beams of light so that each atom scattered at most one photon. By preparing the atoms in different quantum states, they were able to modify what information the atoms obtained about the path of the photons. The researchers thus confirmed the predictions of quantum theory: The more information was obtained about the path (i.e. the particle nature) of light, the lower the visibility of the interference pattern was. ..."

From the abstract:

"We study light scattering of single atoms in free space and discuss the results in terms of atom-photon entanglement and which-way information.

Using ultracold atoms released from an optical lattice, we realize a Gedanken experiment which interferes single photons scattering off of Heisenberg uncertainty-limited wavepackets.

We unify the free-space and trapped-atom pictures by measuring the light scattered during wavepacket expansion and show the coherence properties of the scattered light is independent of the presence of the trap. Our experiment demonstrates the potential of using atomic Mott insulators to create single-atom wavepackets for fundamental studies."

Famous double-slit experiment holds up when stripped to its quantum essentials | MIT News | Massachusetts Institute of Technology "MIT physicists confirm that ... light has two identities that are impossible to see at once."

Coherent and Incoherent Light Scattering by Single-Atom Wave Packets (no public access)

Coherent and incoherent light scattering by single-atom wavepackets (preprint, open access)