Convert between bitstring probabilities and joint Z moment expectations.

Parameters:p (ndarray) – An array that enumerates bitstring probabilities. When flattened out p = [p_00...0, p_00...1, ...,p_11...1]. The total number of elements must therefore be a power of 2. The canonical shape has a separate axis for each qubit, such that p[i,j,...,k] gives the estimated probability of bitstring ij...k.
Return type:ndarray
Returns:z_moments, an np.array with one length-2 axis per qubit which contains the expectations of all monomials in {I, Z_0, Z_1, ..., Z_{n-1}}. The expectations of each monomial can be accessed via:
<Z_0^j_0 Z_1^j_1 ... Z_m^j_m> = z_moments[j_0,j_1,...,j_m]