Sub-Shot Noise Measurements with an Acousto-Optic Modulator

The shot noise limit is a fundamental lower limit on the sensitivity of any measurement and is defined by nature. We propose an experiment in which we measure the difference current from each heterodyne detector and find that the result is a sinusoidal function of the path length difference between the the two heterodyne systems. For certain values of the path length, we expect to overcome the shot noise limit set by the local oscillator. Here we review our experiment and report on the current experimental progress.