Cold atoms are the main ingredients of modern optical clocks, that can reach an accuracy of 10-18 seconds, against 10-15 s of atomic clocks. At LENS the research on optical clocks aims to simplify and reduce the size of the equipment to make them transportable, e.g. to send them in space. At lower temperatures, ultracold atoms in a condensed phase allow to perform atomic interferometry experiments and Strontium can be a useful quantum sensor to measure forces due to macroscopic source masses on micrometer distances, e.g. to investigate inverse-square Newton's law or Casimir effect.