Increase of signal-to-noise ratio in weak value measurements

Abstract

We present a method for improving the signal-to-noise ratio of optical weak measurement techniques by recycling the non-post selected light.We designed a system that allows input photons to cycle through a Sagnac interferometer twice, effectively doubling the detected intensity. A deflection as small as 20 picoradians is discernible. The expected improvement for a shot-noise-limited system is a factor of ã2; however, we observed a larger signal-to-noise ratio enhancement (1.73) which can occur for systems limited by technical noise. [for a video of the talk given by Prof. Kwiat at the Aharonov-80 conference in 2012 at Chapman University, see quantum.chapman.edu/talk-5.]