Deterministic generation of hybrid entangled states using quantum walks

In recent times, hybrid-entanglement (HE) between a qubit and a coherent state has demonstrated superior performance in various quantum information processing tasks, particularly in quantum key distribution. Despite its theoretical advantages, efficient generation of such states in the laboratory has been a challenge. Here, we introduce a deterministic and efficient approach for generating HE states using quantum walks. Our method achieves a remarkable fidelity of $99.9\%$ with just $20$ time steps in a one-dimensional split-step quantum walk. This represents a significant improvement over prior approaches for probabilistic generation of HE states with fidelity as low as $80\%$. Our scheme not only provides a robust solution to the generation of HE states but also highlights a unique advantage of quantum walks, thereby contributing to the advancement of this burgeoning field. Moreover, our scheme is experimentally feasible with the current technology.