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Comment by mkl95 | Hacker News Reader

> Japan will compensate companies to keep secret patents with potential military applications under proposed legislation

> The patents under review in the proposed economic security legislation will include technology that can help develop nuclear weapons, such as uranium enrichment and cutting-edge innovations like quantum technology, the financial daily said.

It seems that they are basically asking companies to be quiet if they are making something for military use. Not sure about the quantum part.

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> It seems that they are basically asking companies to be quiet if they are making something for military use. Not sure about the quantum part.

The US does that too, if you try to file a patent for something that has military applications.

https://slate.com/technology/2018/05/the-thousands-of-secret...

I'm not sure if the US even provides compensation like the Japanese government is going to.

Quantum navigation. Quantum accelerometers theoretically enable hyper-accurate guidance systems immune to external jamming.

https://en.wikipedia.org/wiki/Quantum_compass

That sounds interesting. Iirc inertial navigation systems are also a key component in missiles that don't enable radar (and so reveal their presence) until they're right on the target ("pitbull"). I don't know how much of a limiter the INS is there, but it could possibly lead to more precise missiles with less warning time.

Missiles yes, but it is more practical for submarines. More accurate submarine navigation means they can navigate closer to the bottom/coast without using sonar and can fire ballistic missiles accurately without surfacing.

> Quantum accelerometers theoretically enable hyper-accurate guidance systems immune to external jamming

Can one jam normal accelerometers? I don't see how.

I think it's rather that normal accelerometers aren't precise enough to replace GPS (well, radio/satellite based positioning systems), which are possible to jam.

Normal guidance systems, which rely on non-accelerometer input, are vulnerable to external jamming.

Certainly GPS is, but I don't see how inertial or celestial are.

Celestisl is impractical for modern weapons. INS just isnt accurate enough over long periods (think of subs submerged for months).

> Celestial is impractical for modern weapons.

My understanding is ICBMs use it. It could be used by UAVs to get within a few miles of the target, and then use visual / IR / radar to to get to a more precise location.

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