Time-frequency entanglement is highly regarded in quantum technology due to its high-dimensional entanglement and resilience to practical disturbances such as phase and polarization. It has been extensively discussed as a promising approach for developing novel protocols in quantum key distribution (QKD) and enabling long-distance quantum communication. In this work, we utilize a Franson interferometer to verify the time-frequency entanglement of photon pairs generated from spontaneous parametric down-conversion (SPDC). We observed a high visibility of 94% in the nonlocal two-photon quantum interference, confirming the time-frequency entanglement. To demonstrate the advantages of time-frequency entanglement in long-distance fiber networks, we further conducted entanglement distribution experiments using the fiber infrastructure in National Central University. Remarkably, after transmitting through a 2.64 km fiber, we achieve an interference visibility of 87.4%, surpassing the classical limit of 70.7% by a significant margin. Our work realizes an efficient time-frequency entanglement source, verifies entanglement distribution in a real-application field, and further establishes the foundation for future applications of time-frequency encoding in long-distance quantum communication or high-dimensional quantum computing.
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