Sensing rotations with multiplane light conversion

We report an experiment estimating the three parameters of a general rotation. The scheme uses quantum states attaining the ultimate precision dictated by the quantum Cramér-Rao bound. We realize the states experimentally using the orbital angular momentum of light and implement the rotations with a multiplane light conversion setup, which allows one to perform arbitrary unitary transformations on a finite set of spatial modes. The observed performance suggests a range of potential applications in the next generation of rotation sensors.