qiskit.quantum_info.partial_trace¶
-
partial_trace(state, qargs)[source]¶ Return reduced density matrix by tracing out part of quantum state.
If all subsystems are traced over this returns the
trace()of the input state.- Paramètres
state (Statevector or DensityMatrix) – the input state.
qargs (list) – The subsystems to trace over.
- Renvoie
The reduced density matrix.
- Type renvoyé
- Lève
QiskitError – if input state is invalid.