Generation of Competitive and Coexisting Two Pairs of Biphotons in Single Hot Atomic Vapor Cell

The non‐classical states of light serve as a potential candidate for emerging quantum information process. A processing trend to enhance its scalability is to integrate multiple nonlinear processes with the dressed‐state picture into a single device, and therefore, are useful for quantum computations. Here, a novel method is proposed to experimentally achieve the generation of coexisting two pairs of narrow‐band biphotons by two four‐wave mixing processes in a single hot rubidium vapor cell. Based on the photon‐atom nonlinear interfaces, the generated biphotons exhibits genuine entanglement in time–energy. Meanwhile, the nonlinear susceptibility with the dressed‐state picture decides the temporal correlation of the biphotons wave packet as a damped periodic Rabi oscillation, suggesting the property of the high‐dimensional time–energy entangled state. Such a high‐dimensional entangled state also is an efficient way to enhance information carrying capacity. By alternating two nonlinear susceptibilities in a single device, respectively, there exists a competition of the generation rate between such two pairs of biphotons. Moreover, both generated two pairs of biphotons that violate the Cauchy–Schwarz inequality and show their non‐classical behavior.