Upon his return to the States, he wanted to work on promoting quantum mechanics in American universities. He accepted a position as an associate professor at the University of California, Berkeley.
Before he started working at the university, he was diagnosed with a mild form of tuberculosis. To cure himself, he went with his brother Frank for several weeks to a ranch in New Mexico that he leased and eventually bought. He called it "Perro Caliente". He later said that "physics and the desert were his two great loves".
