Frequency-multiplexed photon pair sources for long-distance quantum communication

The Quantum Internet enables sharing the entanglement between any two points and a multitude of applications. A major challenge is to overcome loss of photons which serves as quantum state carriers in optical fibers. Quantum repeaters have emerged as a solution to this issue. Frequency multiplexing has been proposed as a promising approach to enhance the communication rate, enabling the simultaneous transmission of multiple photons across distinct frequency channels. To achieve this, it is necessary to develop frequency multiplexed quantum memories (QMs) to be installed in quantum repeater nodes and photon sources to be coupled with the QMs. We adopt atomic frequency comb (AFC) generated in Pr³⁺:YSO as QM, where multiple AFCs are created within the inhomogeneous broadening of Pr³⁺:YSO, allowing for efficient frequency-multimode storage.

In this study, we will provide a comprehensive update on the development of our cavity photon pair sources compatible with our frequency-multiplexed QMs and telecom C-band.