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Nonlinear Feedback in Josephson Circuit Optimization: Application to a Kerr-Reversal JTWPA

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Based on a feed excerpt; full article content has not been acquired. Source evidence retrieved 09/10/2026, 04:13:25 UTC.

Briefings

A new optimization method for Josephson-based microwave devices uses nonlinear feedback to correct pump-induced effects like impedance renormalization and Kerr-induced phase mismatches. The approach applies harmonic balance simulations in two stages: fast linear simulations for initial configuration selection, followed by nonlinear simulations to optimize operating conditions. This method was tested on a Josephson traveling-wave parametric amplifier with a reversed-Kerr architecture, validated against experimental gain measurements. A key finding is that the difference between linear and pumped response values of a metric based on input reflection coefficient serves as a candidate feedback observable, exhibiting features similar to the gain landscape.

Key points

• Josephson Circuits Optimizer uses two-stage harmonic balance simulations: fast linear simulations for initial configuration selection followed by nonlinear simulations for operating condition optimization.
• The method introduces a nonlinear feedback extension that transfers information from the pumped response back to the linear optimization stage to correct pump-induced effects.

Context and limitations

The approach was validated against experimental gain measurements for a specific reversed-Kerr architecture. The metric based on input reflection coefficient was evaluated excluding configurations with insufficient third-harmonic suppression, and the specific discrepancy observed remains a candidate feedback observable rather than a confirmed universal metric.

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