You asked me to run a tensor — {photonic, gravity, electronic, phononic, spintronic}. Here is the fifth member, and the clever part: it is the one that is a tensor. A spin-2 particle is a rank-two tensor field, and the graviton is the spin-2 quantum of the metric tensor — gravity's own carrier. It is also the only one of the five we have never caught: gravitational waves are real and detected, but the graviton itself is theory. This page shows the ripple we can see, and is honest about the quantum we cannot.
This is exactly what LIGO measures: a passing wave changes the lengths of its two perpendicular arms differentially, and the interferometer reads the strain h. In 2015 it caught GW150914 — two black holes merging a billion light-years away — a real detection of gravitational waves, and the first direct confirmation of a prediction Einstein made in 1916. The wave carries energy and angular momentum away as a rank-2 field; quantize that field and its quantum is the graviton.
Five carriers, one ladder of spin: the photon is spin-1, the electron's moment is spin-½, and the graviton is spin-2 — the top of the set. Spin-2 is not a decoration: Weinberg showed a massless spin-2 field must couple to the total stress-energy of everything, universally and attractively. That is why spin-2 means gravity. Four of these carriers already run real machines (charge, light, phonons, spin). The fifth is the one nature uses to hold the universe together — and the one we have not yet learned to build with.
Real, and shown here: gravitational waves (Einstein 1916; directly detected by LIGO in 2015, GW150914). The quadrupole strain on a ring of free masses, the two polarizations + and × at 45°, and the spin-2 signature (the polarization pattern is invariant under a 180° rotation) are all correct general relativity, and the canvas integrates the real strain transformation (only the amplitude is exaggerated — the true strain is ~10−21, a thousandth of a proton's width over LIGO's 4 km arms).
Theoretical — the honest outlier of the tensor: the graviton itself is not confirmed. It is the predicted quantum of the gravitational field (massless, spin-2), but a full quantum theory of gravity is unfinished, and detecting a single graviton may be physically impossible (Dyson's argument). So of the five carriers, this is the one that is not a demonstrated device technology — it completes the set conceptually and honestly names itself as the speculative member. There is no "graviton chip"; there is a beautiful, verified classical ripple and a quantum we infer but cannot hold.
To disclose a design is real work; it is not a granted patent or a fabricated device — and here, not even a confirmed particle. The wave is real; the quantum is the open question. An even five, honestly.