Ising Dynamics for Programmable Threshold Sensing in Wireless Devices

Abstract The dynamics of interconnected networks of Ising spins have been exploited in the past to achieve various heterogeneous goals, such as modeling ferromagnetic materials and phase transitions, and analyzing spin glasses. Ising machines, comprised of dissipatively coupled nodes capable of emulating the behavior of ferromagnetic spins, have also garnered increasing attention as analog computing engines surpassing the sequential processing constraints of von Neumann architectures. However, the incorporation of Ising dynamics into radio frequency (RF) wireless technologies has yet to be explored, especially in terms of their potential to enhance modern wireless sensing capabilities. In this work, we demonstrate a passive wireless sensor exploiting Ising dynamics to accurately implement threshold sensing. This component, which we name “Sensing Parametric Ising Node” (SPIN), correlates the occurrence of violations in a sensed parameter with transitions in the coupling state of two parametric oscillators (POs) acting as Ising spins. This feature renders SPIN’s accuracy unaffected by distortions in its input and output signals caused by multipath and it permits to reduce co-site interference. We discuss the principles of operation, the implementation, and the performance of a SPIN prototype used for temperature threshold sensing. We also show how coupling SPIN’s two POs with a microelectromechanical resonant sensor enables the wireless reprogramming of SPIN’s threshold. Through the demonstration of SPIN, this work introduces a new paradigm in wireless sensing by presenting the core unit of a novel passive computing system that can facilitate decision-making well beyond what is possible with existing passive technology.