pygsti.tools.matrixtools.unitary_superoperator_matrix_log

pygsti.tools.matrixtools.unitary_superoperator_matrix_log#

unitary_superoperator_matrix_log(m, mx_basis)#

Construct the logarithm of superoperator matrix m.

This function assumes that m acts as a unitary on density-matrix space, (m: rho -> U rho Udagger) so that log(m) can be written as the action by Hamiltonian H:

log(m): rho -> -i[H,rho].

Parameters:

  • m (numpy array) – The superoperator matrix whose logarithm is taken

  • mx_basis ({'std', 'gm', 'pp', 'qt'} or Basis object) – The source and destination basis, respectively. Allowed values are Matrix-unit (std), Gell-Mann (gm), Pauli-product (pp), and Qutrit (qt) (or a custom basis object).

Returns:

A matrix logM, of the same shape as m, such that m = exp(logM) and logM can be written as the action rho -> -i[H,rho].

Return type:

numpy array