High power generation with distributed Josephson-junction arrays

We have experimentally coupled emission from a distributed series array of 1968 wide Josephson junctions to an on-chip 10.8 Ohm load and detected 0.16 mW at 240 GHz. This result is achieved by reducing the parasitic inductance associated with shunt resistors so that junctions with critical currents of 23 mA are effectively shunted at the operating frequency. This power is less than the 1.3 mW expected from theory due to the presence of a large impedance mismatch. Optimization of the load design will allow the detection of mW power.