Quantum gas microscopy for single atom and spin detection

A particular strength of ultracold quantum gases is the range of versatile detection methods that are available. As they are based on atom–light interactions, the whole quantum optics toolbox can be used to tailor the detection process to the specific scientific question to be explored in the experiment. Common methods include time-of-flight measurements to access the momentum distribution of the gas, the use of cavities to monitor global properties of the quantum gas with minimal disturbance, and phase-contrast or high-intensity absorption imaging to obtain local real-space information in high-density settings. Even the ultimate limit of detecting each and every atom locally has been realized in two dimensions using so-called quantum gas microscopes. In fact, these microscopes have not only revolutionized detection—they have also revolutionized the control of lattice gases. Here, we provide a short overview of quantum gas microscopy, highlighting the new observables it can access as well as key experiments that have been enabled by its development.