Polarization-entangled photon-pair source in the near-NIR for free-space QKD
Abstract
Quantum key distribution (QKD) is a family of techniques for distributing encryption keys by the exchange of quantum signals. In particular, polarization-entangled photon-pairs are widely used for the most secure form of QKD. To extend the range of QKD networks, satellite-based optical links have been mooted. This would require the placement of entangled photon-pair sources on satellites, where the photons are then transmitted to ground receivers. A number of proof-of-principle experiments for key distribution using entangled photons already exist, but most of the sources of entangled photon-pairs are not ready for field deployment or operation on spacecraft. We propose to raise the technology readiness level of entangled photon-pair sources. In this project we will study and test a source of polarization-entangled photon-pairs that is robust, bright, and compatible with single-mode freespace key distribution. This project intends to build polarization-entangled photons using bulk nonlinear optical crystals that are pumped by free-running laser diodes. To improve ruggedness of the photon pair source, the crystals will be single-domain crystals, most likely based on Beta-Barium Borate or similar materials. These nonlinear materials do not change their optical properties very much over commonly experienced temperature ranges, and also available from a wide variety of commercial suppliers. As part of the study, we will attempt to map the collection of photon-pairs into single-mode fibers. This will include both conventional fibers with a solid-core, as well as more novel, photonic crystal fibers, with the aim of boosting the observed photon-pair rate for every milliwatt of pump power that is used in the system. By combining known techniques for assembling the optical components, with novel single-mode collection techniques, we hope to demonstrate a viable path to robust and bright photon-pair sources that can enable entanglement-based QKD on a variety of platforms.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 02, 2017
- Source ID
- FA23861714008
Entities
People
- Alexander Ling
Organizations
- Air Force Office of Scientific Research
- National University of Singapore
- United States Air Force