Our CIM Expedition project is organized around four major themes: Fundamentals, Generalizations, Applications, and Benchmarking. While Fundamentals and Benchmarking focus mainly on developing broader and deeper understandings of current CIM prototypes, Generalizations and Applications explore CIM’s potential to advance both practical technology and new concepts in computer engineering. A snapshot of our research plan is provided by the graphic below.

The theme of CIM Fundamentals encompasses detailed analysis of the physical operating principles of CIM hardware — what are the rate-limiting steps in optimization dynamics of current prototypes, how do they relate to the combinatorial structure of specific problem instances, and how do technical issues of noise and finite precision factor into computational performance? We plan to address such questions using an array of approaches based in quantum optics, dynamical systems theory, and random matrix theory.

The closely-related theme of CIM Generalizations draws upon these same core disciplines, but expands the research in the direction of manifestly quantum phenomena and potential improvements of the CIM architecture. If we work to further suppress decoherence in advance CIM prototypes can we sustain entanglement and observe non-classical interference effects that accelerate rate-limiting dynamics? Can we adapt ideas from multi-layer neural networks, message passing algorithms, and/or reservoir computing to improve upon the current approach for Ising-type optimizations? Can we broaden the class of problems for which CIM-type hardware is best suited?

In the CIM Applications theme we return to focus on capabilities of current CIM prototypes but will work to elaborate detailed and rigorous connections between specific needs of practical applications and CIM’s unique computational strengths and weaknesses. We will tackle issues such as efficient mapping from application-native to CIM-native problem formulations, as well as related issues regarding approximations and feasibility constraints. In this area we will work closely with application domain experts including collaborators in industry.

Our CIM Benchmarking activities will be led by our group at USRA/NASA, building on their extensive expertise in evaluating the performance of emerging quantum computing technologies and formulating fair comparisons against conventional digital computing approaches, considering both time-based metrics and auxiliary resource costs such as energy consumption. The results of this work will help us to draw a more complete and reliable picture of the trajectory of CIM prototype performance relative to other unconventional computing technologies. They will also enable us to analyze more thoroughly how classes of optimization problem instances map to different types of phase space topologies for the dynamic evolution of physical CIM hardware, which is critical for our fundamental understanding of CIM scaling.

The above graphic illustrates the rough “org chart” of how our CIM Expedition’s constituent research groups map onto the four themes describe above, represented by rows of the table. The columns of the table indicate general domains of disciplinary expertise, highlighting the interdisciplinary nature of our effort spanning from device physics to core areas of computer science and applied mathematics.