Abstract
Realization of long-distance quantum communication through the quantum repeater network requires a combination of some key elements, including a multiplexed quantum memory for storage of entanglement and a telecom photon for propagation of information through the fiber. Although impressive experimental advances have demonstrated the individual elements, combining these key capabilities together and realizing them in a single experimental system remains a significant challenge. Here, we report an experimental realization of long-distance entanglement between a multiplexed quantum memory with 49 individually accessible memory cells and a telecom photon after transmission in a 10-km optical fiber. Excitation of an atomic ensemble generates narrow-band polarization entanglement between a telecom photon of 1530-nm wavelength and another photon of 780-nm wavelength, which is then stored into a memory cell of a multiplexed atomic quantum memory and read out after a controllable delay. The entanglement is verified through quantum-state tomography after quantum storage in the atomic memory and fiber transmission of the telecom photon. This experiment demonstrates an important step towards realization of long-distance quantum communication networks.
- Received 21 June 2019
- Revised 16 October 2019
DOI:https://doi.org/10.1103/PhysRevX.9.041033
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Long-distance quantum communication over a network with quantum repeaters—essential devices for extending the range over which information can propagate—requires a combination of several key capabilities, including a quantum memory for storage of entanglement and a telecom photon for the propagation of information through an optical fiber. Although impressive experimental advances have demonstrated the individual elements, combining these capabilities together in a single experimental system remains a significant challenge. Here, we report an experimental realization of long-distance entanglement between a quantum memory with 49 individually accessible memory cells and a telecom photon after transmission in a 10-km-long optical fiber.
We achieve a multicell quantum memory through spatial multiplexing in a single macroscopic atomic ensemble. Another atomic ensemble provides a light source to generate narrow-band polarization entanglement between a telecom photon of 1530-nm wavelength and another photon of 780-nm wavelength. The telecom photon is propagated through the 10-km fiber and the other photon is stored in a memory cell of the multiplexed quantum memory and read out after a controllable delay. The entanglement is verified with a fidelity of around 80% after quantum storage in the atomic memory and fiber transmission of the telecom photon.
This experiment demonstrates an important step toward the realization of long-distance quantum communication networks.