# qiskit.quantum_info.gate_error¶

gate_error(channel, target=None, require_cp=True, require_tp=False)[source]

Return the gate error of a noisy quantum channel.

The gate error $$E$$ is given by the average gate infidelity

$E(\mathcal{E}, U) = 1 - F_{\text{ave}}(\mathcal{E}, U)$

where $$F_{\text{ave}}(\mathcal{E}, U)$$ is the average_gate_fidelity() of the input quantum channel $$\mathcal{E}$$ with a target unitary $$U$$.

Parameters
• channel (QuantumChannel) -- noisy quantum channel.

• target (Operator or None) -- target unitary operator. If None target is the identity operator [Default: None].

• require_cp (bool) -- check if input and target channels are completely-positive and if non-CP log warning containing negative eigenvalues of Choi-matrix [Default: True].

• require_tp (bool) -- check if input and target channels are trace-preserving and if non-TP log warning containing negative eigenvalues of partial Choi-matrix $$Tr_{\mbox{out}}[\mathcal{E}] - I$$ [Default: True].

Returns

The average gate error $$E$$.

Return type

float

Raises

QiskitError -- if the channel and target do not have the same dimensions, or have different input and output dimensions.