# General 3 qubit states

1. Feb 9, 2015

### m~ray

How do I write the general form of a 3 qubit mixed state ? It has 63 variables. Well one way is to use bloch vectors. So basically we take 3 single qubit mixed states (3 variables each) and tensor product them. Then we add the 2 qubit correlators and 3 qubit correlator terms. Finally we can divide it by its trace (to make its trace 1). It is hence unit trace and hermitian. However positive semidifinite condition is violated.

2. Feb 14, 2015