Quantum position verification: loss and entanglement

Quantum position verification: loss and entanglement

Seminar author:Llorenç Escolà-Farràs

Event date and time:01/23/2025 02:30:pm

Event location:Seminar Room, GIQ

Event contact:

Abstract: In the talk, I will introduce the concept of quantum position verification (QPV), which consists of verifying the location of an untrusted prover using quantum mechanics and special relativity. I will summarize significant results from the literature and present new findings, with special emphasis on how signal loss threatens the security of quantum cryptography when protocols lack loss-tolerance. In QPV, even small loss rates can compromise security!
I will analyze the exact loss-tolerance of the QPV protocol based on BB84 states, which becomes insecure if attackers pre-share a single EPR pair. While adding classical information can mitigate this, it requires a transmission rate exceeding 50%, making it impractical over long distances. Finally, I will present a  result that makes arbitrary photon loss irrelevant to security, and combining it with the BB84-based protocol, offers a promising, implementable solution.