"Ricardo is a huge talent," coach Felix Magath said of the 19-year-old.
"He was a starting player for Zurich and played a role in Europe as well. He has also already played for the national team."
Magath, also Wolfsburg's sporting director and known for his tough discipline and gruelling training sessions, was often criticised for his frantic transfer activity at previous club Schalke.
Since Christmas he has signed seven other players, including Franco-Ivorian forward Giovanni Sio, Portuguese midfielder Vieirinha and Macedonian forward Ferhan Hasani.
Magath, who led Wolfsburg to their first Bundesliga title in 2009, has had a less successful second stint after joining late last season.
Wolfsburg are 12th at the halfway point in the Bundesliga, four points clear of the relegation playoff spot. The league resumes next week with Wolfsburg entertaining Cologne.