Bell Nonlocality Across a Simulated Horizon: CHSH Violation in a Gate-Based Qubit-Truncated Pair-Creation Analog on NISQ Hardware

We report a gate-based quantum circuit that implements a qubit-truncated analog of pair creation, inspired by Hawking radiation phenomenology, and demonstrate certified Bell nonlocality on IBM Quantum hardware (ibm_fez, Heron R2, 156 qubits). Using a two-mode squeezing (TMS) gate mapping |00⟩ to cos(θ/2)|00⟩ + sin(θ/2)|11⟩, we generate entangled pairs across a designated ‘horizon’ position in a 20-qubit chain.
Main results: CHSH Bell parameter S = 2.290 ± 0.010 (29.8σ shot-noise; >22σ conservative with systematics), entanglement witness W = 2.838 ± 0.004, and Bell-state fidelity F(|Φ⁺⟩) = 96%. Bootstrap resampling (10,000 iterations) confirms robustness (100% of samples violate classical bounds).
Important caveat: this is a protocol demonstration for gravity-inspired entanglement certification on NISQ hardware, not a faithful simulation of Hawking radiation (no thermal spectrum / vacuum structure).