Author Archives: Mateus Araújo

First Valladolid paper is out!

A couple of days ago I finally released the first Julia project I had alluded to, a technique to compute key rates in QKD using proper conic methods. The paper is out, and the github repository is now public. It’s … Continue reading

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I got a Ramón y Cajal!

I’m quite happy, this is pretty much the best grant available in Spain, it gives me a lot of money for 5 years, including a PhD student and a postdoc. But the reason I’m posting about it here is to … Continue reading

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MATLAB is dead, long live Julia!

Since I’ve first used MATLAB I have dreamt of finding a replacement for it. Not only it is expensive, proprietary software, but also a terrible programming language. Don’t get me wrong, I’m sure it was amazing when it was invented, … Continue reading

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The smallest uninteresting number is 198

A well-known joke/theorem is that all natural numbers are interesting. The proof goes as follows: assume that there exists a non-empty set of uninteresting natural numbers. Then this set has a smallest element. But that makes it interesting, so we … Continue reading

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SDPs with complex numbers

For mysterious reasons, some time ago I found myself reading SeDuMi’s manual. To my surprise, it claimed to support SDPs with complex numbers. More specifically, it could handle positive semidefiniteness constraints on complex Hermitian matrices, instead of only real symmetric … Continue reading

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SDPs are not cheat codes

I usually say the opposite to my students: that SDPs are the cheat codes of quantum information. That if you can formulate your problem as an SDP you’re in heaven: there will be an efficient algorithm for finding numerical solutions, … Continue reading

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Redefining classicality

I’m in a terrible mood. Maybe it’s just the relentless blackness of Austrian winter, but I do have rational reasons to be annoyed. First is the firehose of nonsense coming from the wormhole-in-a-quantum-computer people, that I wrote about in my … Continue reading

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The death of Quanta Magazine

Yesterday Quanta Magazine published an article written by Natalie Wolchover, Physicists Create a Wormhole Using a Quantum Computer. I’m shocked and disappointed. I thought Quanta Magazine was the most respectable source of science news, they have published several quality, in-depth … Continue reading

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Doing induction like a physicist

If something is true for dimension 2, it doesn’t mean much. We know that 2 is very special. The set of valid quantum states is a sphere, we can have a basis of unitary and Hermitian matrices for the Hilbert … Continue reading

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Do not project your relative frequencies onto the non-signalling subspace

It happens all the time. You make an experiment on nonlocality or steering, and you want to test whether the data you collected is compatible with hidden variables. You plug them into the computer and the answer is no, they … Continue reading

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