Dynamic Microwave Impedance of Dc-Biased Josephson Fluxonic Diode in the Presence of Magnetic Field and RF Drive

Josephson Fluxonic Diode (JFD) provides a very nonlinear characteristic in comparison with a long Josephson junction at microwave frequencies. This nonlinearity is highly accentuated by creation and dynamics of vortex-antivortex pairs in two disparate modes of operation; forward and reverse-bias. Experimental detection of microwave frequencies through this device is not solely dependent on the geometry and seems to change drastically with the different operating condition. This paper attempts to understand the microwave characteristic of this device with respect to its bias and control current and rf-exposed boundary conditions defined in RCSJ model of JFD. Based on the simulation results, for a finite length of a JFD excited by a low-amplitude microwave signal below its plasma frequency, control current increases the rate of vortex-antivortex pair generation and fine-tunes the microwave resistance (R
_ω
) up to an order of magnitude more than its zero magnetic field resistance (R
₀
). Under this circumstance, adding the bias current which can move generated vortex-antivortex pairs causes a substantial increase up to three orders of magnitude compared to R
₀
either in forward or reverse-bias, while damping coefficient 1/√β
_c
(β
_c
is Stewart-McCumber parameter of Josephson junction) can limit this increase. It has also been shown that the variation of polarity, frequency, or amplitude of incoming microwave signal can impact on the impedance due to its relation with pair generation rate and so causes variations in observed impedance both in linear and nonlinear form. According to the results, low-microwave impedance of a JFD can be multiplied externally using biasing sets to match with high-impedance sources, which justifies its detection mechanism at microwave frequency.