Polykarp Kusch (German: [ˈpoːliˌkaʁp ˈkuʃ]; January 26, 1911 – March 20, 1993) was a German-American physicist who shared the 1955 Nobel Prize in Physics with Willis Eugene Lamb for his accurate determination that the electron magnetic moment was greater than its theoretical value, thus leading to reconsideration of and innovations in quantum electrodynamics.

He continued his education at the same alma mater, studying for his Ph.D. under mentorship from F. Wheeler Loomis and after defending his thesis titled "The Molecular Spectrum of Caesium and Rubidium", graduated from it in 1936.

In 1935, prior to moving to the University of Minnesota, Kusch married his girlfriend, Edith Starr Roberts.

He worked on molecular beam resonance studies under I. I. Rabi, then discovered the electron anomalous magnetic moment.

He expanded into chemical physics and continued to publish research on molecular beams.