Traveling Wave Parametric Amplification without Dispersion Engineering

Josepshon Traveling Wave Parametric Amplifiers (J-TWPAs) are promising platforms for realizing quantum-limited broadband amplification of microwave signals. However, substantial gain in such systems is attainable only when strict constraints on phase matching the signal, idler and pump waves are satisfied -- this is rendered particularly challenging in the presence of nonlinear effects, such as self- and cross-phase modulation, which scale with the pump intensity. A recent notable approach to alleviate this problem involves introducing resonant elements into the transmission line and pumping near the stop band of the modified dispersion curve. Here we propose a new system that can realize large broadband gain without employing any dispersion engineering. The efficiency of the resultant four-wave mixing process allows achieving >20dB gain over few-GHz bandwidths with much shorter lines than previous implementations, making the proposed architecture particularly appealing from a fabrication perspective. Additional optimization, coupled with flexibility in pump engineering, can be used to modify the gain profile in view of targeted applications, such as optimizing maximum gain vs constant-gain bandwidth.