In this talk I would present our recent experimental observation of an exotic molecule, Rydberg macrodimer, which is a bound state of two highly excited Rydberg atoms. The subnanoscale size of typical diatomic molecules hinders direct optical access to their constituents. Rydberg macrodimers, however, feature interatomic distances easily exceeding optical wavelengths. We have direct microscopic observation and detailed characterization of such molecules in a gas of ultracold rubidium atoms in an optical lattice. The bond length of about 0.7 micrometers matches the diagonal distance of the lattice. By exciting pairs in the initial two-dimensional atom array, we resolved more than 50 vibrational resonances. Using our spatially resolved detection, we observed the macrodimers by correlated atom loss and demonstrated control of the molecular alignment by the choice of the vibrational state. At the end, I would also introduce other experimental possibilities about macrodimers.
 Hollerith et al. Science, 364, 664 (2019)