# Discord for partially decohered bell state

To illustrate discord and its use, Zurek in his paper on discord (NB pdf) gives example of a partially decohered bell state i.e. $$\rho_{AB}=\frac{1}{2}(|00\rangle\langle 00|+|11\rangle\langle 11|) + \frac{z}{2}(|00\rangle \langle 11|+|11\rangle \langle 00|)$$ using the measurement basis for Alice's side. $$\{\cos\theta |0\rangle + e^{i\phi} \sin\theta |1\rangle,\ e^{-i\phi} \sin\theta |0\rangle + \cos\theta |1\rangle\}$$ He plotted it in the Fig.1.

Now my problem is that I have not been able to reproduce this result. Here is what I got. I can not seem to locate what could be the source problem. The Mathematica code which I used is here. Can anyone see what might be going wrong here.

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Your state $\psi_{AB}$ is not the same as Zurek's partially decohered Bell state in Eq. (17). (In particular, the latter is a mixed state.) –  Norbert Schuch Nov 24 '13 at 15:23
@Norbert Sorry I wrote it wrong, but you can see in mathematica code that I used it correctly. Thanks I'll correct it now. –  The Imp Nov 24 '13 at 22:54
The Mathematica code cannot be viewed without requesting some kind of permission. –  Norbert Schuch Nov 25 '13 at 9:40
@NorbertSchuch I have changed it's privacy please. this works now. I checked it by signing out. please try it now. –  The Imp Nov 25 '13 at 12:01

I have confirmed with Zurek, he told me that it was wrong (at least the period-wise) and it has been pointed out many times by other people including Animesh Dutta.

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Could you provide references to, at least, the other rebuttals? –  Emilio Pisanty Apr 4 '14 at 10:57