Unconventional computing devices are increasingly of interest as they can
operate in environments hostile to silicon-based electronics, or compute in
ways that traditional electronics cannot. Mechanical computers, wherein
information processing is a material property emerging from the interaction of
components with the environment, are one such class of devices. This
information processing can be manifested in various physical substrates, one of
which is granular matter. In a granular assembly, vibration can be treated as
the information-bearing mode. This can be exploited to realize "polycomputing":
materials can be evolved such that a single grain within them can report the
result of multiple logical operations simultaneously at different frequencies,
without recourse to quantum effects. Here, we demonstrate the evolution of a
material in which one grain acts simultaneously as two different NAND gates at
two different frequencies. NAND gates are of interest as any logical operations
can be built from them. Moreover, they are nonlinear thus demonstrating a step
toward general-purpose, computationally dense mechanical computers.
Polycomputation was found to be distributed across each evolved material,
suggesting the material's robustness. With recent advances in material
sciences, hardware realization of these materials may eventually provide
devices that challenge the computational density of traditional computers.

本文旨在通过研究基于颗粒堆积的力学计算机，探讨在不依赖于量子效应的情况下实现多逻辑计算的 “聚合计算” 模式，并演示了一种由颗粒进化而成的物质，用于同时实现两个不同频率下的两个 NAND 门。这种聚合计算方法可以在不同的物理基质上实现，为未来材料科学领域提供了有趣的前景。