Measurement of two-polarity detector for ballistic computing

The size and number of computations are steadily increasing, leading to growing concerns about the energy consumption associated with them. Reversible computing, which operates differently from conventional (irreversible) logic, has the potential to address this issue. We previously reported ballistic reversible gate circuits [1] that use flux polarities (fluxon and antifluxon) in long Josephson junctions (LJJs) to represent bit states. We have previously engineered LJJs that contain 47 zJ low-energy fluxons, and measured those fluxons in a 4K cryogen-free refrigerator. Here, we present a new detector capable of sorting fluxons by polarity into separate circuit arms and performing readout. Fluxons representing logical 1 are directed to the upper arm and read by one single-polarity detector; antifluxons representing logical 0 are sent to the lower arm and read by another single-polarity detector. The two-polarity detector is highly beneficial for future gate operations requiring polarity distinction, including a ballistic flip flop (B-FF). Our B-FF, in which we will show the fabrication layout, will be solely powered by the bit state inertia of the incoming bits in LJJs. The two-polarity detector can route bits from the interface to different readout circuits based on their polarity, enabling bit-state distinction.

[1] Wustmann W, Osborn KD. Reversible fluxon logic: Topological particles allow ballistic gates along one-dimensional paths. Physical Review B. 2020 Jan 31;101(1):014516.