Microwave Isolation through Adiabatic Mode Conversion in Superconducting Coupled Transmission Lines

Non-reciprocal devices are essential for isolating superconducting quantum circuits from the noisy electromagnetic environment while allowing measurement and control. For the past decade, ferrite-based circulators and isolators have been predominantly used to protect superconducting quantum circuits, but major limitations associated with large permanent magnets motivate a non-ferrite and scalable solution. Here we discuss a new scheme that utilizes adiabatic mode conversion in coupled nonlinear Josephson junction transmission lines to realize broadband isolation without magnetic elements, allowing integration with current superconducting qubit technology. We report on progress toward implementing this device.