Single-atom absorption imaging

Abstract

Absorption of light is a fundamental process in imaging. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the quantum limits of absorption imaging. Here we report the first absorption imaging of a single isolated atom, the smallest and simplest system reported to date. Contrasts of up to 3.1(3)% were observed in images of a laser cooled ¹⁷⁴Yb⁺ ion confined in vacuum by a radio-frequency Paul trap. This work establishes a new sensitivity bound for absorption imaging with a 7800x improvement over the contrast previously observed in imaging a single molecule.