Towards Quantum Repeater based on Atomic Vapor Cell

Quantum technology is one of the most important fields including quantum communication, quantum computing, and quantum sensing. In this regard, entanglement is an essential resource for quantum information processing. Optical losses in fiber degrade the fidelities of entangled states, which must be reduced for effectively distributing the entanglement over large distances. Quantum repeaters provide a solution to this issue with a seemingly straightforward yet challenging requirement: entangling telecom-wavelength photons with quantum memory. [1] With this issue, atomic vapor cells are promising candidates for constructing both quantum light sources and quantum memory due to their experimental simplicity, scalability, and efficient atom-photon interaction.

Ran Finkelstein and Omir Davison et al. [2,3] demonstrated Doppler-free fast ladder memory (FLAME) in room-temperature atomic vapor cells filled with ⁸⁷Rb isotopes. The FLAME configuration is Doppler-free and possesses a wavelength suitable for our telecom biphoton source [4]. We store and retrieve 780 nm Gaussian pulses and optimize the memory efficiency for storing 780 nm photon polarization-entangled with 1529 nm photon. We believe that the combination of our quantum memory with a telecom-wavelength bi-photon source from an atomic vapor cell paves the way for demonstrating quantum nodes for efficient transportation of quantum photonic states.