This method is used to support passing a matrix, a state vector,
or a computational basis state as a representation of a state.
If an numpy array, if it is of rank 2 (a matrix),
then this is the density matrix. If it is a numpy array of rank 1
(a vector) then this is a state vector. If this is an int,
then this is the computation basis state.
The number of qubits for the density matrix. The
density_matrix_rep must be valid for this number of qubits.
The qid shape of the state vector. Specify this argument
when using qudits.
The numpy dtype of the density matrix, will be used when creating
the state for a computational basis state (int), or validated
against if density_matrix_rep is a numpy array.
Numerical tolerance for verifying density matrix properties.
A numpy matrix corresponding to the density matrix on the given number
of qubits. Note that this matrix may share memory with the input
ValueError if the density_matrix_rep is not valid.