Why hasn’t this been done before
Six reasons (descending importance):
- Cultural orthogonality. Antenna engineers minimise coupling. CIM researchers came from optics. Nobody crossed both.
- Wired-coupling lower resistance. The non-optical CIM community (Roychowdhury Berkeley, Chris Kim Minnesota, Shukla Notre Dame) all went wired electrical because SPICE-model-friendly and VNA-testable. Radiative coupling needs full-wave FDTD simulation which is computationally expensive and outside standard IC EDA flow.
- Reconfigurability harder for radiative. Wired J is set by switchable lumped components. Radiative J is set by fabrication geometry + per-tile resonance modulation; the inverse design problem (find varactor states such that realised J ≈ target J) is non-trivial.
- Adjacent RIS field optimises for radiation. Reconfigurable Intelligent Surfaces (RIS) and metamaterial antenna arrays do use varactor-tuned dipole/patch arrays, but the objective is radiation (steer a beam, shape a wavefront) not internal energy minimisation. Mapping RIS to Ising solver has not been formally published.
- Tooling cost. Full-wave EM simulation at array scale only became affordable at 16-tile / 64-tile in the last few years.
- Calibration wall. Anyone who tried hit the FDTD-to-Hardware Calibration Wall and didn’t publish the failure.
Prior art to verify in DD
Aggressive prior-art search needed in three places:
- Chinese RIS / metamaterial Ising literature (last 3 years, large active community, English visibility weak)
- US defence labs — MIT Lincoln Lab, JHU APL, DARPA TRIAD / MORPH / OPTIMA programmes (would publish little but final reports may list dead branches)
- EU H2020 / Horizon Europe photonic + RF unconventional-computing project deliverables
If those return clean, the “no one’s been here before” claim survives. If a 2022 Chinese paper or DARPA final report turns up doing exactly this, the IP wedge collapses fast.
Adjacent prior art (known)
- SWIM (YIG + microwave components, Nature Comm Phys 2023) — microwave-band Ising machine, different physical medium (yttrium iron garnet), <100 spins
- 50-spin SAW Ising machine (Nature Comm Phys 2025) — surface acoustic wave, microwave-band, <100 spins
- Nature Electronics 65nm CMOS varactor Ising (2025) — wired coupled-oscillator with varactor tuning, closest direct prior art on the coupling-modulation mechanism
Why now (technology readiness)
- 5G mmWave silicon (24-40 GHz) pushed CMOS-RF and RF-SOI processes into production at GF, TSMC, Samsung with mature design kits (Sivers Wireless, Movandi, WiFi 7)
- Intel Agilex 9 RF DACs shipping since 2023 — the control layer needed to programme antenna-array varactors at GHz speeds is off-the-shelf
- Full-wave FDTD simulators on commodity HPC enable 64-tile + 256-tile EM characterisation at affordable cost