High linearity superconducting radio frequency magnetic field detector

A signal linearizer, comprising:

• a plurality of Josephson junction circuits, each Josephson junction circuit having a signal input and a respective circuit output;
• configured as a Superconducting Quantum Interference Device (SQUID) comprising at least one first Josephson junction and an inductive loop, the inductive loop being configured to inductively couple a signal, having a shunt across the loop, comprising at least one second Josephson junction having a critical current, operating below the critical current in a presence of the signal, and having non-linear electrical conductance with respect to a potential across the shunt, wherein the shunt is effective to modify a transfer function of the SQUID to produce a linearized transfer function;
• and
• a combiner, configured to combine the respective circuit outputs of the plurality of Josephson junction circuits to produce a combined signal having a reduction of total harmonic distortion of at least 6 dB with respect to each of the respective circuit outputs.