PROBLEM Historically, hydrogen has been employed in a variety of industrial chemical processes. Typically, the purity requirements for this hydrogen have tolerated contaminant levels ranging from ppm to low percentages, depending upon the application. The use of hydrogen has now expanded into novel applications such as alternative fuel for use in transportation and stationary electrical generat...

We classify the entanglement of two-mode Gaussian states according to their degree of total and partial mixedness. We derive exact bounds that determine maximally and minimally entangled states for fixed global and marginal purities. This characterization allows for an experimentally reliable estimate of continuous variable entanglement based on measurements of purity.