Given a separable 3-qubit state
φ = φ0 ⊗ φ1 ⊗ φ2
with
φi= ai0|0> + ai1|1>,
|0>, |1> being the computational base. φ thus can be written as
φ = b000|000> + b001|001> + b010|010> + b011|011> + b100|100> + b101|101> + b110|110> + b111|111>
with
|ijk> = |i> ⊗ |j> ⊗ |k>
bijk = a0ia1ja2k.
Now let some bijk be given, defining an arbitrary 3-qubit state
φ = b000|000> + b001|001> + b010|010> + b011|011> + b100|100> + b101|101> + b110|110> + b111|111>
Question 1
How is Schmidt decomposition to be applied to the tensor B = (bijk) to find out if the state is separable?
Question 2
Assuming that the following five possibilities of entanglement are possible
φ0, φ1 and φ2 entangled,
φi separable, φj and φk entangled,
φ0, φ1 and φ2 separable,
how do I calculate the corresponding coefficients, i.e. in case (3)
φ = φ0 ⊗ φ1 ⊗ φ2.
where I want to know the six coefficients aij in
φi= ai0|0> + ai1|1>.