Osheroff joined the Laboratory of Atomic and Solid State Physics at Cornell University as a graduate student, doing research in low-temperature physics. Together with David Lee, the head of the laboratory, and Robert C. Richardson, Osheroff used a Pomeranchuk cell to investigate the behaviour of He at temperatures within a few thousandths of a degree of absolute zero. They discovered unexpected effects in their measurements, which they eventually explained as phase transitions to a superfluid phase of He. Lee, Richardson and Osheroff were jointly awarded the Nobel Prize in Physics in 1996 for this discovery.