Academic participants:
Gilles Brassard, Nicolas Godbout, Thomas Jennewein, Hoi-Kwong Lo, Kevin Resch, Wolfgang Tittel, Gregor Weihs.
Partners:
BBN technologies, idQuantique, MagiQ, Perimeter Institute, Centre for Applied Crytographic Research, Nortel Networks.
The goal of Quantum Key Distribution (QKD) is to allow two distant parties, Alice and Bob to distill out a secure key from imperfect quantum communications, perhaps corrupted by an eavesdropper. Recent work on security proof for the BB84 protocol, the best-known protocol for QKD, is based on the “entanglement distillation” approach. These security proofs have recently been generalized for imperfect devices but they depend on the type of error happening in realistic devices.
A QKD test-bed is currently in operation at the University of Toronto with generous support from CFI and OIT. Such a test-bed is crucial for the testing of new quantum information devices (single-photon sources and detectors) developed in Canada and overseas and the implementations of new protocols including decoy-state QKD.
We will also construct a free-space QKD link connecting the IQC and the Perimeter Institute for Theoretical Physics. Since air is not birefringent it is easiest to use polarization as a qubit. Further, we will have to decide whether to use weak laser pulses or a source of entangled photon pairs. The advantage of the latter is that we wouldn’t require a fast modulator in this case, but the key creation rate may be low for a compact source, these will be thoroughly investigated.
We will also investigate multi-party cryptography using multi-wavelength quantum key distribution systems. The path to multi-user large scale quantum key distribution likely includes the use of multiple wavelengths in the same fibre. Different wavelengths can be routed with minimal loss to their respective targeted user. Wavelength multiplexing can also be used to increase the bit generation rate by using several channels in parallel.
These testbeds will be used to understand the practical difficulties of implementing quantum technologies and feedback with the project B5 on benchmarking and A5 on error correction.
This project will interact with project QC4 on verification and certification. BBN technologies, idQuantique, MagiQ will be collaborating in this project through QuantumWorks networking programs focused on implementations of quantum cryptographic systems.