THURSDAY, May 21

Special IQI Seminar, 2:45 PM - 3:45 PM, 74 Jorgensen
"Quantum Cryptography in Real-life Applications," Yi Zhao, Ph.D. Candidate, University of Toronto, Department of Physics.

Abstract:

Quantum key distribution (QKD) provides unconditional communication security that is guaranteed by fundamental laws of physics. Commercial quantum cryptosystems have been available on market, and are applied in the recent Swiss election. As QKD steps into our daily life, a natural concern arises:

Are current QKD systems really secure?

In this talk, I will present my experimental and theoretical studies in seek of answering the above question. Experimentally, several assumptions that are widely made in security proofs will be tested and enhanced. Theoretically, some imperfections in practical devices and their security consequence will be analyzed. I will discuss our achievements include: 1) the first experimental demonstration of decoy state QKD; 2) the first experimental demonstration of active phase randomization in QKD; 3) the first quantum hacking demonstration; and 4) the first security proof for QKD with an unknown and untrusted source. Our achievements significantly improved the security of real-life QKD systems, although the ultimate solution to guarantee the unconditional security of QKD in real-life applications is yet to be discovered.