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Quantum Goblins, my first PRA |
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Written by Aharon Brodutch
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Thursday, 10 June 2010 00:00 |
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Danny and me just had our paper on quantum goblins published in PRA. This is the first publication from my Phd, and my first PRA.
After comments from the editor we changed the name from (the arXive version's) "Quantum discord and local demons" to "Quantum discord, local operations, and Maxwell’s demons"
In the paper we discuss three different types of quantum discord, the first is the original introduced by Zurek, the second was introduced by Zurek in relation to Maxwell's demons. We introduced the third in relation to a slightly different formulation of the same Maxwell's demon idea. During our conversations with various people we discovered that many people don't realize that Zurek's second version of discord is different from the first one, so we used the opportunity to point out the difference. We also showed that all three versions of discord agree on which states have zero discord.
This work really started happening when I was too lazy to calculate discord in some 3x3 system, Danny and me then found that there is a very easy way to verify if a system has zero discord (it's in the paper). We then decided that maybe this method could give us a different version of discord, this different version of discord turned out to be very cool because it was related to thermodynamics. We basically showed that this third version of discord is the difference in the amount of work that can be done by Maxwell's demons with access to the whole system (non local demons) and demons with access to just part of the system (local demons) since the local demons are not as "strong" as the non local ones , we called them goblins (It started the other way around, but Alex Terno told us that goblins are weaker then demons).
We have a few other results in the paper relating different types of discord to various other things, generally trying to make the whole idea of different types of discord less confusing and showing the physics related to each one. Finally we also showed that by looking at the discord of a density matrix (made up of probabilities of having different pure states) we can't know if the states which make up the density matrix are locally distinguishable.
Before we published I gave some talks on this work, one talk can be found here.
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