# qiskit.quantum_info.mutual_information¶

mutual_information(state, base=2)[source]

Calculate the mutual information of a bipartite state.

The mutual information $$I$$ is given by:

$I(\rho_{AB}) = S(\rho_A) + S(\rho_B) - S(\rho_{AB})$

where $$\rho_A=Tr_B[\rho_{AB}], \rho_B=Tr_A[\rho_{AB}]$$, are the reduced density matrices of the bipartite state $$\rho_{AB}$$.

Parameters
Returns

The mutual information $$I(\rho_{AB})$$.

Return type

float

Raises
• QiskitError -- if the input state is not a valid QuantumState.

• QiskitError -- if input is not a bipartite QuantumState.