[andutu]

I've skimmed some literature on Quantum Crypto and from my understanding the outstanding issues currently are 1. How to make these work over long distances and 2. How to implement features found in PKI authentication (though QKD schemes are theoretically secure against MITM attacks, there still isn't a quantum cryptography scheme yet to ensure that you are talking to a non-adversary). There have been advances with the 1st problem, but the 2nd is trickier. Tbf, you don't strictly need PKE to have secure communication between 2 parties (look at Section 6 in https://signal.org/docs/specifications/sesame/).

A lot of real world implementations of quantum crypto have been with respect to satellite communications, which makes sense. The satellite is usually built by the same actors who set up the communication links from the ground the satellite and quantum particles can be transmitted by laser. But as the article points out, it probably won't see widespread use for a while. There was a paper that came out recently called "How (not) to Build Quantum PKE in Minicrypt" (https://arxiv.org/abs/2405.20295) and from my limited understanding of it, a quantum PKE system will likely have very little components from classical crypto incorporated into it. Not to mention that specially built devices have to be installed at ISPs, data centers, etc. for this to work.

Work in this space is valuable as a hedge against a world where all conventional crypto is broken. It also helps advance work in quantum mechanics more generally and other fields in physics and it's generally very interesting :)

edit: grammar corrections