[bob1029]

Measuring photons in this manner gives you the best randomness. It is effectively a quantum technique. A PN junction is (mostly) classical.

The specific mechanism is mentioned in the article:

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

> Although there is only one electronic transition from the excited state to ground state, there are many ways in which the electromagnetic field may go from the ground state to a one-photon state. That is, the electromagnetic field has infinitely more degrees of freedom, corresponding to the different directions in which the photon can be emitted. Equivalently, one might say that the phase space offered by the electromagnetic field is infinitely larger than that offered by the atom. This infinite degree of freedom for the emission of the photon results in the apparent irreversible decay, i.e., spontaneous emission.

[dragontamer]

I've been told that reverse shot noise from a PN junction is quantum in nature.

It is possible for an electron to spontaneously gather enough voltage to break through a PN junction backwards. This shows up as a very noisy current measured in microamps.

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A forward bias PN junction might not be quantomly random. I'll have to research more. But a reverse bias PN junction is almost certainly quantum in nature.

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IMO, this is all just PN junction noise. Maybe LEDs are better than Zener diodes for noise. I'm pretty sure that noise characteristics are a guess and check methodology, it's all PN junctions of slightly different shapes after all.

[cubefox]

The question is whether quantum mechanical noise could have a conceivable advantage over classical noise. I strongly suspect: no. Classical noise is already factually unpredictable, so the theoretical unpredictability (assuming no hidden variable theories I guess) of quantum noise doesn't add anything.

[bob1029]

Classical noise is only unpredictable if you are lacking the necessary physical information to make an accurate prediction. Otherwise, it is always predictable.

Quantum noise is not based in any kind of physical information in the same way. It is intrinsically random. The "randomness" isn't merely a side effect of a bunch of physical phenomena. You cannot compromise a QRNG even if you had perfect knowledge of the state of every particle in the system over time.

https://www.jpmorgan.com/technology/technology-blog/certifie...

[cubefox]

> Classical noise is only unpredictable if you are lacking the necessary physical information to make an accurate prediction. Otherwise, it is always predictable.

Since you are always lacking that necessary physical information, it is always unpredictable. If it were otherwise, we would already know whether hidden variable theories of quantum mechanics (which lack intrinsic randomness) are correct or incorrect. But we don't know that. So intrinsic randomness doesn't make a difference to us. So quantum noise is useless.

[charcircuit]

>Quantum noise is not based in any kind of physical information

This sounds like more of a limitation of the model you are using than a limitation of reality.