Single-Atom Resolution Achieved in DLR Quantum Sensor Experiment

Researchers at the DLR site in Hanover, in collaboration with Leibniz University, have achieved single-atom resolution in a quantum sensor, bringing the technology closer to the fundamental Heisenberg limit of precision. The team, led by Carsten Klempt, reports demonstrating operation of an atomic quantum sensor by entangling atoms, a feat previously considered fundamentally challenging and reliant on quantum mechanical correlations beyond conventional intuition. This advance relies on a novel fluorescence detection method using six intersecting laser beams to minimize atomic movement and heating, significantly increasing the signal from individual atoms. To prove control over the system at this single-particle level, the researchers observed the Hong-Ou-Mandel effect, a quantum interference phenomenon typically seen with photons; through multi-particle interference, the output states are occupied exclusively by an even number of atoms. These findings, published in Nature Physics, could enable high-precision measurements in future atomic interferometers.

Resolution at the Heisenberg limit requires entanglement, quantum correlations between atoms defying conventional intuition, and the DLR team successfully entangled atoms within a Bose-Einstein condensate to achieve this. This configuration minimizes atomic movement and heating, substantially increasing the signal received from each atom and allowing clear distinction from background noise, ultimately attaining single-atom resolution. This parity signal holds promise for future high-precision measurements in atomic interferometers, potentially expanding the capabilities of quantum sensors beyond current limitations.

The ability to perform such precise measurements on a Bose-Einstein condensate represents a genuine breakthrough, shifting single-particle control from photon-based interferometers to atomic systems and opening new avenues for quantum sensing.