Classical imaging is limited in sensitivity and resolution by the statistical noise properties of the light used to create the images. In everyday life a classical description of light usually suffices; however this leads to limitations on both the sensitivity of detecting objects as well as the resolution with which one can detect them that are not fundamental. Using a quantum mechanical description of the light, "non-classical" light fields can be envisioned that will lead to better detection sensitivity and imaging resolution than with classical light. Using non-linear optical properties of certain materials, non-classical light fields can be created and these fields can be investigated to see how much better they are than the classical limits. Such "quantum illumination" has been shown to be capable of improved detection sensitivity, but has not been demonstrated in an imaging situation before, where very different detector and light-source technologies are required. These techniques are especially useful at very low light levels, and thus are interesting in the field of imaging of live biological tissues where one would like to avoid damage to the tissue.
It has been demonstrated that four-wave mixing in atomic vapors can generate light with interesting quantum properties, and do so under conditions where non-trivial imaging is possible. This project takes advantage of the development of this light source to investigate three distinct ideas: the "SU(1,1)" interferometer which potentially exceeds the sensitivity of conventional interferometers, the copier-phase sensitive amplifier (a low-noise optical amplifier for images), and quantum illumination for remote sensing. The extent to which the advantages of quantum illumination and coherent detection can be achieved in practice will be investigated. The work involves the investigation of newly introduced quantum techniques in the context of interferometric sensing and imaging, and it allows the further development of quantum-noise-limited imaging and detection. Quantum entanglement of the light beams could allow improvements in imaging, and have an impact on the study of quantum information processing techniques. These techniques are especially useful at very low light levels, and thus are interesting in the field of imaging of live biological tissues in order to avoid damage to the tissue.
