Atom camera: super-resolution scanning microscope of a light pattern with a single ultracold atom.

Tomita, T; Chew, Y T; Villela, R A; Mahesh, T P; Sakai, H; Nishimura, K; Ando, T; de Léséleuc, S et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

Sub-micrometer light patterns play a pivotal role in biology, biophysics, and AMO physics, yet their in situ characterization is limited in spatial resolution and sensitivity. Here, we present an atom camera with a single ultracold atom in an optical tweezer as a scanning probe. Measuring the energy shift on the spin states with the long coherence time and polarization-sensitive transitions yields highly sensitive, high-resolution 2D imaging of both intensity and polarization ellipticity. We characterize the polarization of a tightly-focused beam, observing its non-trivial profile. The spatial resolution is fundamentally limited by the atom's position uncertainty, suppressed down to quantum fluctuations (~25 nm) in the motional ground state of the tweezer, with an experimentally obtained upper bound of σ ≤ 96(4) nm. This method enables imaging beyond the diffraction limit, surpassing previous approaches limited by thermal fluctuations of the atom, and provides a powerful tool for designing and analyzing submicron-scale light patterns.