Transmon qubit in a magnetic field: Evolution of coherence and transition frequency

Quantum bits require isolation from outer fields to maintain their coherence, and the superconducting state is destroyed by magnetic fields. In this work, however, the authors measure a superconducting transmon qubit in relatively large magnetic fields. By demonstrating quantum coherence up to field values of 40mT, new avenues in hybrid systems and sensing applications based on superconducting quantum circuits are opened up.