[Un]known Information in Quantum Uncertainty Wonmin Son (Sogang University) Uncertainty principle is at the heart of basic construction of quantum mechanics. Contrary to the common textbook formulation, there is more than single way to express quantum uncertainty relation. It is because the concept of uncertainty is quite abstract to be quantified. Uncertainty, as an incompleteness of knowledge, can be characterized based upon the standard deviation of a statistical distribution or the information characterized by entropy. However, it is not yet clear which quantification of the quantum uncertainty is superior in various situations. In this talk, we review the historical trajectory of the formulation of quantum uncertainty principle and provide quantitative comparison between them. Knowing that the whole formalism of quantum optics is based upon the Heisenberg uncertainty relation, it is interesting to identify how much the description of quantum state of light is viewed differently in the framework of quantum uncertainty defined by Shannon¡¯s entropy.