Partially entangled
Partially entangled states are those entangled states where measuring one qubit does not completely determine what the other qubit will be. 1
# Example
Consider the following state of two qubits: $$\frac{\sqrt 3}{2\sqrt2}\ket{00} + \frac{\sqrt 3}{2\sqrt2}\ket{01} + \frac{\sqrt 3}{4}\ket{10} + \frac{1}{4}\ket{11}.$$
If we measure only the left qubit, we get:
- $0$ with probability $3/4$, and the state collapses to $$\frac{1}{\sqrt2}(\ket{00} + \ket{01}) = \ket{0}\frac{1}{\sqrt2}(\ket{0} + \ket{1}).$$
- $1$ with probability $1/4$, and the state collapses to $$\frac{\sqrt3}{2}\ket{10} + \frac{1}{2}\ket{11} = \ket{1} \left(\frac{\sqrt 3}{2}\ket{0} + \frac{1}{2} \ket{1} \right).$$
So, we can see that measuring the left qubit does affect the right qubit. If we measure the right qubit, we may get $0$ or $1$, with probabilities $50:50$ or $0.75:0.25$. So, even though measuring the left qubit affected the right qubit, it did not completely determine what a measurement of the right qubit would yield.