Spin Wave Threshold Gate

TL;DR

This work targets energy efficiency in data processing by moving beyond interference-based spin-wave logic to Threshold Logic (TL) inspired spin-wave computing. It introduces the Spin Wave TL Gate (SWTLG), which implements an $n$-input TL function by applying $n$ phase rotations plus a threshold phase shift $\psi$ to a single spin wave, with outputs determined by the sign of the net phase shift. The authors formalize the TL mapping with $f(x)=\sum_{i} w_i x_i - \psi$ and $F(x)=\text{sgn}(f(x))$, and validate the approach through a micromagnetic Full Adder designed with two TL gates and 4–5 phase-shifters per gate, achieving correct outputs for all input combinations. Compared to a standard $MAJ3$-based FA, the TL-based design offers potential reductions in transducer count and enables DC-phase-shift control, suggesting advantages in area, power, and manufacturability for scalable spin-wave logic. The results point toward a practical, low-power spin-wave computing paradigm with robust phase-based weighting and thresholding capabilities.

Abstract

While Spin Waves (SW) interaction provides natural support for low power Majority (MAJ) gate implementations many hurdles still exists on the road towards the realization of practically relevant SW circuits. In this paper we leave the SW interaction avenue and propose Threshold Logic (TL) inspired SW computing, which relies on successive phase rotations applied to one single SW instead of on the interference of an odd number of SWs. After providing a short TL inside we introduce the SW TL gate concept and discuss the way to mirror TL gate weight and threshold values into physical phase-shifter parameters. Subsequently, we design and demonstrate proper operation of a SW TL based Full Adder (FA) by means of micro-magnetic simulations. We conclude the paper by providing inside on the potential advantages of our proposal by means of a conceptual comparison of MAJ and TL based FA implementations.

Figures (10)

• Figure 1: Basic threshold logic gate.
• Figure 2: SW phase shift based threshold logic gate.
• Figure 3: Dispersion relation (\ref{['DispersionRelation']}) plot for a 200nm wide and 9nm thick CoFeB waveguide using the parameters specified in IntroSpinComp.
• Figure 4: $FA$$C_{out}$ evaluation TL gate structure.
• Figure 5: SW phase shift induced by a single 200nm wide phase-shifter when making use of the parameters in IntroSpinComp. The relation is linear around no applied field point and becomes less linear for larger field values.