# qiskit.quantum_info.partial_trace¶

partial_trace(state, qargs)[Quellcode]

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.

Parameter
Rückgabe

The reduced density matrix.

Rückgabetyp

DensityMatrix

Verursacht

QiskitError – if input state is invalid.