qiskit.aqua.utils.get_subsystem_density_matrix

get_subsystem_density_matrix(statevector, trace_systems)

Compute the reduced density matrix of a quantum subsystem.

Parameters

• statevector (list|array) – The state vector of the complete system
• trace_systems (list|range) – The indices of the qubits to be traced out.

Returns

The reduced density matrix for the desired subsystem

Return type

numpy.ndarray