Stephan Thelen is an American-born, Swiss-based composer, guitarist, and mathematician known for his involvement in the fringes of classical, progressive rock, jazz, ambient, and various other forms of experimental music. Active since the early 1990s, Thelen has been involved in a wide range of projects including the experimental rock bands Radio Osaka and Sonar. Since releasing Broken Symmetry in 2002, he has recorded numerous solo projects and become increasingly involved in modern classical composition. He was commissioned by the Kronos Quartet to compose a piece, "Circular Lines," for their Fifty for the Future project. The piece later appeared, as recorded by Kronos Quartet, on Thelen's ambitious 2020 release World Dialogue.