After his studies in Hamburg, Siena and Berlin and his doctoral work, Grau lectured at the Humboldt University Berlin, was a guest researcher in several research labs in Japan and USA and following his post doctoral lecture qualification (habilitation) in 2003, he worked as professor at different international universities.
Nakon studija u Hamburgu, Berlinu i Sieni i doktorskog rada, Grau je predavao na Humboldt sveučilištu u Berlinu, bio je gost različitih istraživačkih laboratorija u Japanu i SAD-u i nakon poslije doktorske kvalifikacije predavača (habilitation) 2003 g. radio je kao profesor na različitim međunarodnim sveučilištima.