Luhman 16, a binary star system consisting of two brown dwarf stars. The inset is at a much higher resolution to the main picture, with the two stars clearly distinguishable. Source: NASA.
When two point sources of light are close together, we just see a blurry patch. For example, how do we tell if there's one bright star or two dim stars close to each other? Traditionally, the resolution limit on distinguishing point sources of light is called Rayleigh's limit. This project aims to use coherent measurement techniques in quantum optics to overcome the Rayleigh's limit. The goal is to precisely estimate the separation between two closeby point sources.
The Fisher information quantifies the precision of an estimator. The higher the Fisher information, the more precise the estimate. Using traditional measurement techniques, which looks at the intensity distribution from the two point sources, the Fisher information goes to zero as the separation goes to zero. This gives rise to Rayleigh's limit.
However, coherent measurement techniques can be used to overcome this limit. By using an inteferometric setup, we can arrive at an estimate that is independent of the separation. Ideally, this setup will accurately determine the separation of two arbitrarily close point sources of light.