Overview
- Researchers at the University of Science and Technology of China, led by Pan Jianwei with Chao‑Yang Lu, report the experiment in Physical Review Letters.
- The apparatus used a laser‑cooled rubidium atom as a single‑atom interferometer sensitive enough to detect the recoil from a lone photon.
- Loose confinement revealed which‑path information and erased the interference pattern, while tight confinement obscured the path and restored interference, matching Bohr’s prediction.
- By tuning the atom’s momentum uncertainty, the team observed an intermediate regime with partial which‑way information and correspondingly blurred fringes, consistent with quantum theory.
- Reviewers praised the work as a textbook realisation of the century‑old proposal, and researchers highlight its promise for studies of decoherence and entanglement with potential applications in qubits, sensing and communications.