A novel parametric negative-resistance effect in Josephson junctions

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Abstract
The negative‐resistance effect recently predicted for current‐controlled highly damped Josephson junctions is experimentally demonstrated at a frequency of 9 GHz. Characteristically, the pump (or Josephson) frequency is smaller than the amplified one, and the pump mechanism is effective over a broad range of frequencies in contrast to the conventional parametric negative‐resistance effect where the pump frequency exceeds that of signal and idler and where the frequency of operation is limited to a narrow range. The broad‐band feature renders operation uncritical to tuning and bias voltage fluctuations. The fact that the junction is the element of lowest impedance in the circuit alleviates to a degree the matching problem generally encountered with Josephson contacts.