qiskit.quantum_info.partial_trace

partial_trace(state, qargs)

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.

パラメータ

• state (Statevector or DensityMatrix) – the input state.

• qargs (list) – The subsystems to trace over.

戻り値

The reduced density matrix.

戻り値の型

DensityMatrix

例外

QiskitError – if input state is invalid.