Entangled Cesium Lattices in Microgravity: A Quantum-Relativistic Consistency Test of One-Way Light-Speed Isotropy

We propose a quantum-relativistic consistency test of one-way light-speed (OWSL) isotropy using entangled 133Cs atomic clocks in microgravity. A Bell state Ψ+ is generated via a directional Rydberg-blockade “metronome” protocol in a cesium optical lattice and coherently transported 1.000 m using shortcuts to adiabaticity (STA). Because Ψ+ lies in a decoherence-free subspace of the total Hamiltonian, it is exactly stationary under identical local evolution, providing a transport- invariant quantum phase reference. The measured ∆Φ = ΦB− ΦA—the temporal offset between local-oscillator-referenced Ramsey readouts—encodes the photon transit time, while entanglement- verified post-selection rejects trials corrupted by decoherence. Cast within the Mansouri–Sexl test-theory framework, the protocol achieves δc/c∼ 10−5 per 105-trial campaign, reaching 10−6 per 107-trial campaign with 2D lattice parallelisation. The protocol does not resolve the Reichenbach ε-convention; rather, it tests OWSL isotropy self-consistently when the shared phase reference is established by quantum correlations rather than classical signal exchange. Error budgets confirm timing jitter dominates, with gravitational, Sagnac, and vibrational systematics sub-dominant after calibration, at 1.000 m separation in the ISS/BECCAL environment.