Part 2 · bosonic simulation
A richer simulator needs more than two levels per mass. Bosonic modes supply that ladder—but every digital calculation must truncate it.
The gravity-inspired interaction
Sabín digitally simulated a Hamiltonian for two quantum harmonic oscillators whose gravitationally mediated interaction generates a non-standard squeezing process. In the effective form used in this project, pairs of excitations are created or annihilated together:
\[H_{AB}=-\hbar g\left(a_A^{\dagger 2}a_B^{\dagger 2}+a_A^2a_B^2\right).\]A bosonic mode has infinitely many occupation levels, while a qubit register is finite. The simulation therefore selects a maximum occupation. Increasing that cutoff changes both the encoded Hilbert space and the circuit cost.
Convergence before scale
The project first checks the passive gravity/EFT assumptions and then repeats the bosonic calculation at increasing cutoffs. The relevant observables must stop moving within a declared tolerance before the result can be interpreted. A large value of the cutoff is not evidence of correctness by itself.
This stage also exposes a central benchmark-design problem: a physically inspired model can remain classically easy if it has too few modes, too little depth or an exploitable symmetry. Scaling must preserve a meaningful observable while removing accidental shortcuts.
Sources and reproducibility
- Bose et al., A Spin Entanglement Witness for Quantum Gravity
- Marletto & Vedral, Gravitationally Induced Entanglement
- Sabín, Digital quantum simulation of quantum gravitational entanglement
- Pastawski et al., Holographic quantum error-correcting codes
- IBM Quantum documentation: ZNE and PEA
- Public code, numerical reports and full 42-value table on GitHub
Project status: 14 August 2026. Numerical values come from the frozen public research artifacts; claim boundaries are deliberately preserved.