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Understanding Bell’s theorem part 4: the counterfactual version
I was recently leafing through the great book Quantum Computation and Quantum Information, and noticed that the version of Bell’s theorem it presents is not any of those I wrote about in my three posts about Bell’s theorem, but rather … Continue reading
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Measurement results depend on the observer
In today’s arXiv appeared a nice paper by Časlav Brukner, my former PhD supervisor. Its central claim is that one cannot have observerindependent measurement results in quantum mechanics, which I bet you disagree with. But if you think a bit … Continue reading
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A frenquentist’s dream
I’m frequently told that probabilities are the limit of relative frequencies for an infinite number of repetitions. It sounds nice: it defines a difficult concept – probabilities – in terms of a simple one – frequencies – and even gives … Continue reading
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Mixed states and true randomness
Recently two nice papers appeared on the arXiv, the most recent by Galley and Masanes, and the oldest by López Grande et al.. They are both – although a bit indirectly – about the age old question of the equivalence … Continue reading
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What is cool about quantum teleportation?
Everybody™ thinks that quantum teleportation is lame. Even scienceloving xkcd thinks quantum teleportation is lame, and has a comic mocking it: This breaks my heart. I want to actually defend quantum teleportation, and show that Randall Munroe is wrong. Quantum … Continue reading
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Wallace’s version of the DeutschWallace theorem, part 2
To conclude the proof of Wallace’s version of the DeutschWallace theorem, we shall add the Equivalence theorem from the previous post to a pretty weak decision theory, and show that if you are rational and live in a universe described … Continue reading
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Wallace’s version of the DeutschWallace theorem, part 1
One might still be worried about Deutsch’s Additivity. What if it is actually necessary prove the Born rule? In this case one wouldn’t be able to use the Born rule in the ManyWorlds interpretation without committing oneself to stupid decisions, … Continue reading
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Deutsch’s version of the DeutschWallace theorem
With the decision theory from the previous post already giving us probabilities, all that is left to do is add the ManyWorlds interpretation and show that these probabilities must actually be given by the Born rule. Sounds easy, no? But … Continue reading
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Probability from decision theory
There exists a problem in the world, that is even more pressing than the position of cheese in the cheeseburger emoji: namely that nobody™ understands the DeutschWallace theorem. I’ve talked to a lot of people about it, and the usual … Continue reading
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On the morality of blackholing in conferences
Consider the entirely hypothetical situation where you are in a physics conference with really bad wifi. Either because the router has a hard limit in the amount of devices that can connect simultaneously, or the bandwidth is too small to … Continue reading
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