quantum teleportation
Suppose
The composite system becomes$$\frac{\alpha}{\sqrt2}(|0\rangle(|00\rangle + |11\rangle)) + \frac{\beta}{\sqrt2}(|1\rangle(|00\rangle + |11\rangle))$$
- post CNOT$$\frac{\alpha}{\sqrt2}(|000\rangle + |011\rangle) + \frac{\beta}{\sqrt2}(|110\rangle + |101\rangle)$$
- post Hadamard Gate$$\frac{\alpha}{\sqrt2}(|+\rangle |0\rangle |0\rangle + |+\rangle|1\rangle|1\rangle) + \frac{\beta}{\sqrt2}(|-\rangle|1\rangle|0\rangle + |-\rangle|0\rangle|1\rangle)$$
by rewriting we get$$\frac{1}{2}[|00\rangle(\alpha|0\rangle + \beta|1\rangle) + |01\rangle(\alpha|1\rangle + \beta|0\rangle) + |10\rangle (\alpha|0\rangle - \beta|1\rangle) + |11\rangle (\alpha|1\rangle-\beta|0\rangle)]$$
Now Alice measures the first two qubits:
Alice's Qubits post measurement | Transformations Bob has to make |
---|---|
00 | I |
01 | X |
10 | Z |
11 | Y |