#Nonlinear quantum measurements
###Interaction-based measurement
###Alignment-to-orientation conversion
Ground breaking studies of nonlinear quantum measurements, including the first experiment showing sub-Heisenberg scaling of measurement sensitivity, and the first high-precision nonlinear quantum measurement. This is a new topic in quantum metrology, and our work has demonstrated not only that sub-Heisenberg scaling is possible, but that nonlinear interferometers can outperform linear ones for some classes of measurements.