Dynamically preparing robust Bell states by time-boundary engineering

Quantum entanglement is essential for modern quantum information processing. Entanglement gates convert initially non-entangled states into entangled ones by applying time-dependent parametric pulses. While Bell state preparation has been experimentally validated in various platforms, its stability and fidelity are constrained by environmental decoherence and parametric fluctuations.Here, we propose a dynamical framework for preparing robust Bell states by leveraging time-boundary engineering and momentum-space projective measurements within Su-Schrieffer-Heeger (SSH) systems. Employing Lindblad master equation, we theoretically demonstrate that the prepared Bell states exhibit remarkable robustness against both environmental decoherence and parametric time fluctuations, achieving a nearly perfect quantum fidelity, with momentum conservation law governing this robust behavior. To enrich Bell states in momentum space, multi-band SSH models are designed to induce multifold time scattering processes. This time-boundary engineering framework is applicable to both fermionic and bosonic excitations, offering a robust paradigm for generating Bell states in quantum communication and quantum computation.