[etna_ramequin]

Quantum Key Distribution (QKD) requires special (expensive) hardware, so it really doesn’t solve the problem of key size. Moreover, QKD still requires an authenticated channel, so we’ll still need a quantum-resistant authentication scheme.

(All in all, QKD does not have a singular use case)

See https://cyber.gouv.fr/en/publications/should-quantum-key-dis...

[feverzsj]

What about a highspeed quantum channel to transfer all the data?

[etna_ramequin]

Still requires special hardware and authentication, AFAICT.

Plus, you often have got length (hundreds of km) and connection constraints (e.g., only over fibre optic).