Opus 13 is a string quartet that has quickly established itself in the international chamber music scene. Formed in Oslo in 2014 by four teenagers, the ensemble consists of Norwegian violinists Sonoko Miriam Welde and Edvard Erdal, Swedish violist Albin Uusijärvi, and Swedish cellist Daniel Thorell. The quartet is named after Mendelssohn’s A Minor Quartet, Op. 13, which was the first piece they played together.

Opus 13 has won prestigious accolades, including the First Prize at both the Wigmore Hall International String Quartet Competition and the Bordeaux International String Quartet Competition in 2025. They are known for their performances of standard string quartet repertoire as well as their advocacy for Nordic classical and contemporary music. The quartet has collaborated with notable musicians such as Janine Jansen and Alisa Weilerstein and has performed at major festivals across the globe.

They are the founders and artistic directors of Vinterspill på Lillehammer, an annual chamber music festival in Norway. Opus 13 performs on a remarkable set of instruments, including a Stradivari violin and a Storioni violin, both on loan from charitable foundations.