Entanglement of 3-qubit states

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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

  1. φ0, φ1 and φ2 entangled,

  2. φi separable, φj and φk entangled,

  3. 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>.