Which physicist worked in Copenhagen as Bohr's lecturer-assistant from 1926 to 1927?

Werner Heisenberg worked in Copenhagen as Bohr’s lecturer and assistant from 1926 to 1927. He joined Niels Bohr’s institute after earlier research visits and became one of the central figures in the creation of quantum mechanics.

Heisenberg began his appointment as a university lecturer and assistant to Bohr on 1 May 1926. In Copenhagen, he worked closely with Bohr while developing the ideas that led to his uncertainty principle, first formulated in 1927. The institute was an unusually international centre where young physicists debated competing approaches to quantum theory.

Heisenberg’s Copenhagen period followed his breakthrough work on matrix mechanics, developed with Max Born and Pascual Jordan in Göttingen in 1925 and 1926. His collaboration and disagreements with Bohr helped shape what later became associated with the Copenhagen interpretation.

Max Born was Heisenberg’s Göttingen collaborator, while Paul Dirac visited Copenhagen for several months in 1926. Erwin Schrödinger also visited that year, but the lecturer-assistant appointment described in the question belonged to Heisenberg.