# 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
Renvoie

The reduced density matrix.

Type renvoyé

DensityMatrix

Lève

QiskitError – if input state is invalid.