Complex sentence: He then moved to New Jersey where he joined Bell Labs (1956) and started his doctoral studies at Columbia University where he eventually got a Ph.D. in electrical engineering on the dissertation "Properties of high-pass signals" (1965).
Split into simpler sentences: He then moved to New Jersey where he joined Bell Labs (1956) and started his doctoral studies at Columbia University. Theere he earned a Ph.D. in electrical engineering with his dissertation "Properties of High-Pass Signals" (1965).