Utilities (qiskit_addon_slc.utils)

Various utilities.

This module provides a number of utility functions. Some of these exist only temporarily to work around open issues of the Qiskit SDK. When this is the case, they are marked as such and may be removed without deprecation or further notice.

find_indices(circuit, bits_or_instruction, /)

Find the qubit-indices of the provided bit indices or circuit instructions.

Caution

This function is not considered part of the stable API! It will get removed without warning or deprecation when the same functionality is supported natively by the Qiskit SDK. See this issue for more details.

Parameters:

• circuit (QuantumCircuit) – the quantum circuit whose qubit indices to find.

• bits_or_instruction (Bit | CircuitInstruction | Sequence[Bit]) – the bits whose indices to find. If this is a CircuitInstruction, the qubits which this instruction acts upon are used.

Returns:

The indices of the queried bits in the circuit’s registers. If a single bit object was provided, a single int is returned for its index. Otherwise the return type will be a list[int] whose length equals the number of provided bits.

Raises:

TypeError – when an unexpected type of bits_or_instruction gets provided.

Return type:

int | list[int]

generate_noise_model_paulis(instructions, coupling_map=None, circuit=None)

Generate the 1- and 2-weight Pauli terms for each of the unique 2q layer boxes provided.

Parameters:

• instructions (list[CircuitInstruction]) – the output of find_unique_box_instructions(). Any of the provided instructions are assumed to either consists of only measurement gates or correspond to a layer of 2-qubit gate instructions. For the former, the generated noise model will contain only single-qubit X errors, for the latter all 1- and 2-weight Pauli errors on the reduced coupling map will be included.

• coupling_map (CouplingMap | None) – the coupling map of the backend on which the instructions have been laid out. If this is None, a 1d line of qubits is assumed.

• circuit (QuantumCircuit | None) – the transpiled circuit which has been laid out on the provided coupling map. This may only be None when the coupling_map is also None.

Returns:

A dictionary mapping the ref attributes of the InjectNoise annotation of each unique Box to the 1- and 2-weight Pauli terms whose errors are learned for this box.

Return type:

dict[str, QubitSparsePauliList]

get_extremal_eigenvalue(spo, **kwargs)

Finds the extremal eigenvalue of the provided operator.

This converts the provided operator to a sparse matrix whose minimal eigenvalue is required.

Note

The current implementation is definitely not optimized in terms of performance.

Parameters:

• spo (SparsePauliOp) – the operator whose minimal eigenvalue to find.

• kwargs –

  additional keyword arguments for davidson1(). When not specified otherwise, the following defaults will be used:

  • tol: 1e-6

  • max_cycle: 500

  • max_space: 12

  • lindep: 1e-11

  • max_memory: 2000

  Other values will default to PySCF’s default values.

Returns:

A pair indicating whether the Davidson algorithm has converged and the obtained minimal eigenvalue.

Return type:

tuple[bool, float]

iter_circuit(circuit, *, reverse=False, log_process=True)

Iterates over the instructions in a circuit.

Note

This function recurses into BoxOp instructions.

Note

Barriers in the circuit are being ignored.

Parameters:

• circuit (QuantumCircuit) – the circuit to iterate over.

• reverse (bool) – whether to iterate the circuit in reverse order.

• log_process (bool) – whether to log process.

Yields:

Tuples of length four, consisting of the encountered circuit instruction, the canonical qubit indices (i.e. the integer indices of the acted-upon qubits in the context of the input circuit), the InjectNoise attributes: modifier_ref and ref. The latter two items may be None indicating a circuit instruction that was not part of an unrolled BoxOp.

Return type:

Generator[tuple[CircuitInstruction, list[int], str | None, str | None]]

map_modifier_ref_to_ref(circuit)

Iterate a circuit and map InjectNoise annotation references.

Parameters:

circuit (QuantumCircuit) – the circuit to iterate over.

Returns:

A dictionary mapping each InjectNoise.modifier_ref to its InjectNoise.ref.

Return type:

dict[str, str]

remove_measure(circuit)

Remove any Measure operations from the provided circuit.

Note

This function recurses into BoxOp instructions.

Parameters:

circuit (QuantumCircuit) – the circuit whose measurements to remove.

Returns:

The circuit without any Measure operations.

Return type:

QuantumCircuit