Driving a low critical current Josephson junction array with a mode-locked laser

Abstract: We demonstrate the operation of Josephson junction arrays (JJA) driven by optical pulses generated by a mode-locked laser and an optical time-division multiplexer. A commercial photodiode converts the optical pulses into electrical ones in liquid helium several cm from the JJA. The performance of our custom-made mode-locked laser is sufficient for driving a JJA with low critical current at multiple Shapiro steps. Our optical approach is a potential enabler for fast and energy-efficient pulse drive without expensive high-bandwidth electrical pulse pattern generator, and without high-bandwidth electrical cabling crossing temperature stages. Our measurements and simulations motivate an improved integration of photodiodes and JJAs using, e.g., flip-chip techniques, in order to improve both the understanding and fidelity of pulse-driven Josephson Arbitrary Waveform Synthesizers (JAWS).