# qiskit.providers.aer.utils.approximate_quantum_error¶

approximate_quantum_error(error, *, operator_string=None, operator_dict=None, operator_list=None)[source]

Return a QuantumError object that approximates an error as a mixture of specified operators (channels).

The approximation is done by minimizing the Hilbert-Schmidt distance between the process matrix of the target error channel ($$T$$) and the process matrix of the output channel ($$S = \sum_i{p_i S_i}$$), i.e. $$Tr[(T-S)^\dagger (T-S)]$$, where $$[p_1, p_2, ..., p_n]$$ denote probabilities and $$[S_1, S_2, ..., S_n]$$ denote basis operators (channels).

See arXiv:1207.0046 for the details.

Paramètres
• error (QuantumError or QuantumChannel) – the error to be approximated. The number of qubits must be 1 or 2.

• operator_string (string) – a name for a pre-made set of building blocks for the output channel (Default: None). Possible values are 'pauli', 'reset', 'clifford'.

• operator_dict (dict) – a dictionary whose values are the building blocks for the output channel (Default: None). E.g. {« x »: XGate(), « y »: YGate()}, keys « x » and « y » are not used in transformation.

• operator_list (list) – list of building block operators for the output channel (Default: None). E.g. [XGate(), YGate()]

Renvoie

the approximate quantum error.

Type renvoyé

QuantumError

Lève
• NoiseError – if any invalid argument is specified or approximation failed.

• MissingOptionalLibraryError – if cvxpy is not installed.

Note

The operator input precedence is: list < dict < string. If a string is given, dict is overwritten; if a dict is given, list is overwritten. The string supports only 1- or 2-qubit errors and its possible values are 'pauli', 'reset', 'clifford'. The 'clifford' does not support 2-qubit errors.