1305.7051 (K. M. Sundqvist et al.)

The pumpistor: a linearized model of a flux-pumped SQUID for use as a
negative-resistance parametric amplifier    [PDF]

K. M. Sundqvist, S. Kintaş, M. Simoen, P. Krantz, M. Sandberg, C. M. Wilson, P. Delsing

We describe a circuit model for a flux-driven SQUID. This is useful for developing insight into how these devices perform as active elements in parametric amplifiers. The key concept is that frequency mixing in a flux-pumped SQUID allows for the appearance of an effective negative resistance. In the three-wave, degenerate case treated here, a negative resistance appears only over a certain range of allowed input signal phase. This model readily lends itself to testable predictions of more complicated circuits.

View original: http://arxiv.org/abs/1305.7051