rf-current-driven asymmetric 2J-SQUID model with the asymmetry parameters and . Nonhysteretic JJs of RSJ type are employed.
(Color online) Calculated interference patterns of an asymmetric 2J-SQUID having the device parameters of , , and . Line sections connecting the two opposite arrows represent the trajectories of the operation point under the conditions of , , and (a) or (b) .
(Color online) Junction phase evolutions of the asymmetric 2J-SQUID driven by a rf current of and . No bias dc is applied (the zero-biasing condition). (a) Results for . The junction phases oscillate between 0 and , which results in no dc voltage. (b) Results for . The junction phases increase per the rf signal cycle, which results in a finite dc voltage of the step.
(Color online) Junction phase evolution under the same conditions of Fig. 3(b) except . The junction phases increase and then decrease within one cycle of the rf signal. Such imbalance of the phase evolution of also results in the step voltage.
(Color online) Operation parameters plotted on the planes. Open and filled marks represent the positive and negative ZCSSs, respectively. The interference patterns of the 2J-SQUID, the maximum and the polarity-reversed minimum supercurrent values, are also indicated for reference as dashed and dotted curves. Up to the fourth and second ZCSSs are obtained under of 0.05 and 0.1, respectively. Operation margins for a ZCSS decrease with increasing .
(Color online) Microphotograph of a fabricated asymmetric 2J-SQUID. The critical current values of and , which are overdamped by external shunt resistors of 0.40 and , are 0.20 and , respectively. The inductance values corresponding and in Fig. 1 are 2.0 and , respectively.
(Color online) (a) Current-voltage curves of an asymmetric 2J-SQUID irradiated with a rf signal of . The output level of the synthesizer was fixed at . Three curves for of 0.60, 0.0, and are presented. (b) Corresponding numerical curves. was set to . No thermal noise was considered in the simulation.
(Color online) (a) -voltage curve of an asymmetric 2J-SQUID irradiated with a rf signal of . was fixed at . No bias current was applied. (b) Corresponding numerical curve. was set to . No thermal noise was considered in the simulation.
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