Blake C. Stacey is a user on icosahedron.website. You can follow them or interact with them if you have an account anywhere in the fediverse.
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I've started reading this new pre-print: "Why initial system-environment correlations do not imply the failure of complete positivity: a causal perspective" https://arxiv.org/abs/1806.02381
It's interesting in that in a way it introduces a new concept to argue that the textbook way of presenting the quantum-mechanical formalism is actually robust against a critique of it ... twisty
... It also furthers the Rob Spekkens tradition of pointing out, "That thing you thought was all strange and quantum? It actually occurs in classical probability theory."
Relatedly: One reason I'm underwhelmed by the "it from qubit/let's build spacetime out of quantum entanglement" thing some folks have going on now is that they haven't yet really gotten *quantum* about it. For example, they do constructions with stabilizer states, but those are efficiently mimicked by classical means per the Gottesman--Knill theorem.
Attributing all the strangeness of quantum physics to entanglement is a very '90s thing to do, but unlike /Daria/ or /OK Computer/, it hasn't held up very well.
physics level="pretty darn abstruse" Show more
In Masto-meme form:
small brain: unitary operators
larger brain: completely positive maps
glowing brain: potentially negative linear maps
galaxy brain: ... completely positive maps