Collectively Enhanced Universal Photon Blockade
High-purity and bright single-photon sources are important for quantum information processing and precision measurement. We propose a collectively enhanced universal photon-blockade scheme in a multi-emitter two-photon Tavis--Cummings system. Independent coherent drives of the cavity and collective emitter enable destructive interference between two-photon excitation pathways, while collective coupling supplies level anharmonicity. Full-quantum master-equation simulations, the Holstein--Primakoff approximation, and a non-Hermitian probability-amplitude analysis yield the optimal conditions: cavity resonance together with phase and amplitude matching. Compared with a purely collective blockade, the proposed scheme lowers \(g^{(2)}(0)\), and essentially preserves the single-photon population. As the emitter number \(N\) increases, the optimal point remains at \(\Delta_c=0\), while the minimum correlation follows \(g_{\min}^{(2)}(0)\propto N^{-2}\). By contrast, unconventional photon blockade shifts away from resonance as \(N\) increases, limiting its purity improvement and brightness. In the weak-drive regime, universal blockade obeys \(g^{(2)}(0)\propto\varepsilon_a^2\), owing to a higher-order bypass through the three-excitation manifold. The drive strength therefore provides an additional purity--brightness control, although the interference mechanism makes the scheme more sensitive to dissipation-rate mismatch. Our results establish a scalable route to bright, high-purity, and tunable single-photon emission in multi-emitter cavity-QED systems.