Marc Kaplan / VeriQloud
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# Q&A

Q: Who selects a and b (and r and s)?
A: C1 and C2 select their corresponding values

Q: Who is C1 and C2? Are they intermediate devices, or are they subcomponents of A and B?
A: New intermediate devices between A and B.

Q: QKD network without trusted nodes can be built with optical switches. Is there any advantage compared to that?
A: Cost, in Qline intermediate nodes only need modulators

Q: Can you expand how QLine would work on a full Quantum Network (one that transports/shares entangled qubits)? What advantages would it have over simpler approaches?
A: Hard to say, there are other uses once full quantum networks are avialable (see later in talk)

Q: Not sure what limits scalability of the system (inter-node) or number of nodes?
A: Scalability is as always dominated by losses in fiber. So basically, limited by the emitter and detector node. But keep in mind every intermediate node adds losses.

Q: More robustness if intermediate nodes can detect?
A: Adding a detector at intermediate nodes makes it more similiar

Q: please clarify advantage of qline vs "traditional" QKD. cost-effective or more?
A: Scalability - for a given cost you have more nodes; but mainly you don't have trusted nodes.