The Ballistic Asynchronous Reversible Computing (BARC) Model: Superconducting Implementations & Relevance to Quantum Technologies

The modern study of quantum information technology has historical roots in the early explorations of the physics of information processing and concepts for reversible and quantum computation. Key early (pre-1990) investigators in these domains included Landauer, Bennett, Fredkin, Toffoli, Feynman, Deutsch, Margolus, and others.

Although the field has progressed substantially since then, certain early theoretical questions remain under-explored: how to efficiently synchronize self-contained, nearly reversible physical systems whose dynamics implements a computational process?

Fredkin & Toffoli (1981) envisioned ballistic reversible computational mechanisms, and Margolus (1986) considered how parallel quantum models of reversible computing could maintain a definite causal order consistently with relativistic constraints. But these early models were still rather far from practical physical realizations.

A research project pursued at Sandia National Laboratories from 2016–2026 investigated how to make progress by physically realizing reversible computation within a novel quasi-asynchronous model implemented using ballistic transport of flux solitons in Josephson junction (JJ) circuits. This effort culminated with a workable physical design for a (nearly) reversible, computation-universal switch gate primitive.

In this talk, we review this line of work, and discuss its potential applications to quantum computing, including abstract quantum extensions of the theoretical model, as well as potential applications of the classical JJ electronic implementations for control, error correction and readout functionality in engineered quantum computing systems.