Fluxons measured through engineered long Josephson junctions for ballistic computingÂ
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The size and number of computations are increasing at a steady rate, raising concerns about the energy consumption associated with computations. Reversible computing is physically different than conventional (irreversible) logic, and can uniquely address this problem. Adiabatically powered reversible circuits, such as the adiabatic quantum flux parametron (AQFP) and negative-inductance SQUID, currently require energy on the order of zJ per gate. However, these circuits typically use a multiphase AC-clock drive, which is complex relative to industrial CMOS. We are investigating a ballistic reversible logic type known as reversible fluxon logic (RFL). RFL utilizes two possible fluxpolarities (fluxon and antifluxon) in long Josephson junctions (LJJs) for thebit states. Unlike adiabatic types, our gates are ballistic, meaning they are powered by the input bit inertia, eliminating the need for external drive(clock) power within a gate. In this talk, I will introduce the measurement of the engineered LJJs, which serve as components for future ballistic logic gates, acting as standard fluxon waveguides. In contrast to conventional fastSFQ logic, which uses Josephson transmission lines (JTLs) with external bias currents through short JJ, LJJ has no minimum energy cost (in principle) forfluxon transmission. However, due to the discrete LJJ design, the motion of the fluxon may be damped by energy loss from discreteness. From the measurements, we can estimate the energy loss to be on the order of 1 zJ. Two measurement setups (dunk probe setup and cryogen-free refrigerator setup) will be introduced in this talk. The jitter data indicate that the cryogen-free refrigerator measurement environment offers significantly lower RF noise than the dunk probe.