Researchers at the Institute for Molecular Science, National Institutes of Natural Sciences, Japan, have developed a new microscopy technique named the “atom camera”. Using a single ultracold atom as a probe, the method images light fields at the nanoscale. It measures not only light intensity distribution but also directly visualizes optical polarization structures for the first time, achieving sub-100-nm spatial resolution and surpassing the diffraction limit of conventional optical microscopes. The innovation holds promise for quantum computing and other emerging quantum technologies. The paper, titled *Atom camera: super-resolution scanning microscope of a light pattern with a single ultracold atom*, was published in *Nature Communications*.

Conceptual diagram of the atom camera. A single trapped ultracold rubidium (Rb) atom held in optical tweezers scans space to render visible maps of light intensity and polarization distributions.

Precise control of finely structured light fields is essential for quantum technologies. Laser beams are widely used to manipulate quantum states of matter. In neutral-atom quantum computers, microspots and optical lattices formed by lasers play a central role in qubit control. However, direct observation of these light fields has long proven difficult. Such fields are often confined inside vacuum chambers, inaccessible to conventional detectors, while remote imaging through lenses suffers distortion from optical aberrations.

The team trapped a single rubidium atom in optical tweezers and laser-cooled it close to absolute zero to suppress thermal motion. The atom was scanned spatially with nanometer precision to sample the light field point by point.

The atomic spin energy shifts according to local light intensity and polarization at each position. By measuring these energy shifts, researchers reconstruct spatial maps of the light field. The atom acts as a quantum sensor that traverses the light field and converts invisible optical information into measurable data.

Light pattern captured by the atom camera

Moreover, the technique enables direct imaging of polarization structures for the first time. The team found that a simple linearly polarized laser develops complex polarization features near its tight focus; these previously unobservable microscopic variations can now be clearly recorded by the atom camera.

This method offers a brand-new tool for characterizing nanoscale light fields and is broadly applicable in quantum technologies. Especially for neutral-atom quantum computers and quantum simulators, it can precisely characterize and tune laser fields for qubits, which are highly sensitive to both light intensity and polarization.