Single-photon triggered quantum entanglement between two qubits or at least 2000 identical qubits

This paper studies the effect of single-photon light fields on quantum entanglement between two qubits and multiple identical qubits initially in a direct state. For two qubits, we first analyze the impact of the excited state's weight on single-photon-triggered entanglement, finding that excessive weight disrupts this process. We then explore how initial coherence affects entanglement, discovering that maximum initial coherence enables the single photon to achieve maximal entanglement. For multiple qubits, we similarly investigate the effects of the excited state's weight and initial coherence on entanglement control. In large qubit systems, we find that single photons cannot trigger entanglement when excited-state weights exceed ground-state weights or when all qubits are initially in the ground state. Interestingly, single photons can still trigger entanglement between any two qubits in systems with at least 2000 qubits, with the entanglement depending on initial state parameters rather than the number of qubits.