DWDM-Based Effective Group Velocity Dispersion Module for Long-Distance Quantum Communication

Quantum states of light can be used to encode quantum information, and it can be transmitted over free-space or optical fibers for long-distance quantum communication. Since quantum signals or qubits cannot be amplified, long-distance quantum communication often requires pre-conditioning or preparation of the quantum states for a specific group velocity dispersion (GVD) of the desired fiber-optic channel, which is often difficult experimentally. Moreover, in entanglement-based quantum communication, GVD can be used as another degree of freedom to certify an entanglement signature. However, introducing and controlling large GVD with minimal loss is a challenging problem. In this work, we demonstrate a fiber-optic module capable of introducing a desired amount of GVD to the quantum signal and verify its operation using an entangled photon pair at the telecom wavelength. Our GVD module is based on dense wavelength-division multiplexing (DWDM) technology, and it can be easily designed and operated for various quantum communication scenarios, making it a valuable tool in implementing long-distance quantum communication in varying real-world conditions.