With the world increasingly becoming more connected, new technologies are required to ensure that communication is reliable and secure. One such technology is quantum communication, which relies on quantum effects to transmit and secure information. However, such technology is challenging to implement and is still mostly impractical.
Kim et al. developed an experimental quantum communication network connecting multiple users and relying on time-bin entangled qubits for data transmission. The network runs over optical fiber and each user is separated by 60 kilometers.
The authors demonstrated the distribution of high-quality, usable time-bin entanglement to multiple pairs of network users, making the network specifically well-suited for long-distance fiber-optic networks. They believe their work represents significant advances in multiple-user quantum communication technology toward the practical, field-deployable quantum network.
The network is set up with three users, all spaced 60 km apart. The team generated entangled photon pairs using spontaneous parametric down-conversion and generated qubits using the time-bin degree of freedom. Each user was able to communicate with each other user simultaneously and with minimal hardware, as the entangled photons are all generated at a single source and distributed to the users.
The researchers hope their demonstration will translate into practical use of quantum communication networks. Next, the researchers want to focus on reducing noise to enable greater communication distances.
In long-distance quantum communication, preventing entanglement degradation due to noise becomes the key issue. The authors believe their strategy will address the problem of entanglement distribution and significantly advance the field of long-distance quantum communication.
Source: “Quantum communication with time-bin entanglement over a wavelength-multiplexed fiber network,” by Jin-Hun Kim, Jin-Woo Chae, Youn-Chang Jeong, and Yoon-Ho Kim, APL Photonics (2022). The article can be accessed at https://doi.org/10.1063/5.0073040.
