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4 votes
Accepted

Entanglement and teleportation transmission costs

I'm unsure of this exact protocol you're referring to, but if you're interested in the "cost" or reliability of teleportation , then I have some information pertaining to the original setup. ...
Cei328's user avatar
  • 101
3 votes
Accepted

Entanglement Swapping Circuit

There is a mistake in design of the first circuit. Both $X$ and $Z$ gate work when value 1 is in classical register. Gate $X$ should work in case qubit $q_2$ is in state $|1\rangle$. Similarly $Z$ ...
Martin Vesely's user avatar
3 votes
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Swaps in a uniform superposition

Appendix C in this paper provides an algorithm to do this based on a variant of the Fisher-Yates shuffle. The paper provides all the details you need to implement the algorithm in easy to follow steps....
Egretta.Thula's user avatar
2 votes
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Problem about entanglement swapping

I guess the way that I'd start (aside from just getting a computer to do it!) is to remember that the Bell states form an orthonormal basis. So, you can ask, for example, about what the $|\Phi^+\...
DaftWullie's user avatar
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2 votes
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Can pairwise entanglement be converted into tripartite correlations?

No, it is not possible without communication. To see why, consider B and C, and just ignore A -- since they cannot communicate, for anything B and C can do A's presence is irrelevant. Then, B and C'...
Norbert Schuch's user avatar
2 votes

Inner product in terms of Hadamard and controlled SWAP gates

As mentioned in a comment, this is just a standard swap test, which is asked about repeatedly on this site. It corresponds to a circuit which hopefully shows you more clearly which qubits each step ...
DaftWullie's user avatar
  • 59.4k
1 vote

How Quickly Can We Entangle a Pair of Unentangled Qubits Without Using Pre-existing Entanglement?

You can parallelise your proposal. Imagine you have $k+1$ points along a line where points 0 and $k$ are locations $a$ and $b$. Let $k$ be even for the sake of argument. At each even-numbered point $i$...
DaftWullie's user avatar
  • 59.4k
1 vote

How to project on the $\phi^+$ basis when performing entanglement swapping?

Given a bipartite pure state $|\Psi\rangle\equiv \sum_{ij} c_{ij} |i,j\rangle$, to project onto a state $|\Phi\rangle\equiv\sum_{ij} d_{ij}|i,j\rangle$ means to compute the quantity $$\langle \Phi|\...
glS's user avatar
  • 25.6k
1 vote

What would be the procedure if I wish to code entanglement swapping?

I think what you want is in this paper : Fusion-based quantum computation Look at the "Bell fusion" in Fig 2. Basically you measure $X_BX_C$ and $Z_B Z_C$ and that leaves $q_A q_D$ entangled....
unknown's user avatar
  • 2,217
1 vote
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Quick question about Two-qubit SWAP gate from the Exchange interaction

You need to calculate $U=e^{-iHt}$. The trick to doing this is working out the eigenvectors of $H$: there's $|00\rangle$ and $|11\rangle$ with eigenvalues J, and $$ |\Psi^{\pm}\rangle=(|01\rangle\pm|...
DaftWullie's user avatar
  • 59.4k
1 vote

Problem involving entanglement swapping

If you are interested only in the measurements of the system that comprises only 2nd and 3rd qubits, then you could compute the reduced density matrix $\rho_{23}$ on those qubits from the total ...
Danylo Y's user avatar
  • 7,452
1 vote
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Problem involving entanglement swapping

Judging from your computations, the Bell states are $$|B_{00}\rangle = |\Phi^+\rangle = \frac{1}{\sqrt{2}}(|00\rangle + |11\rangle)$$ $$|B_{10}\rangle = |\Phi^-\rangle = \frac{1}{\sqrt{2}}(|00\rangle -...
kludg's user avatar
  • 3,214
1 vote

Entanglement Swapping Circuit

Thanks to Martin Vesely! Now I modify method 1 by using the correct c values. I think I got the right answer. My goal is to see the 1st bit entangled with the 4th bit. As can be seen below, 1st and ...
Dragon123's user avatar
  • 207

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