WhileLoopOp

class WhileLoopOp(condition, body, label=None)

Bases: qiskit.circuit.controlflow.control_flow.ControlFlowOp

A circuit operation which repeatedly executes a subcircuit (body) until a condition (condition) evaluates as False.

Parameters

• condition (Union[Tuple[ClassicalRegister, int], Tuple[Clbit, int], Tuple[Clbit, bool]]) – A condition to be checked prior to executing body. Can be specified as either a tuple of a ClassicalRegister to be tested for equality with a given int, or as a tuple of a Clbit to be compared to either a bool or an int.

• body (QuantumCircuit) – The loop body to be repeatedly executed.

• label (Optional[str]) – An optional label for identifying the instruction.

The classical bits used in condition must be a subset of those attached to body.

Circuit symbol:

     ┌─────────────┐
q_0: ┤0            ├
     │             │
q_1: ┤1            ├
     │  while_loop │
q_2: ┤2            ├
     │             │
c_0: ╡0            ╞
     └─────────────┘

Create a new instruction.

Parameters

• name (str) – instruction name

• num_qubits (int) – instruction’s qubit width

• num_clbits (int) – instruction’s clbit width

• params (list[int|float|complex|str|ndarray|list|ParameterExpression]) – list of parameters

• duration (int or float) – instruction’s duration. it must be integer if unit is ‘dt’

• unit (str) – time unit of duration

• label (str or None) – An optional label for identifying the instruction.

Raises

• CircuitError – when the register is not in the correct format.

• TypeError – when the optional label is provided, but it is not a string.

Methods

add_decomposition	Add a decomposition of the instruction to the SessionEquivalenceLibrary.
assemble	Assemble a QasmQobjInstruction
broadcast_arguments	Validation of the arguments.
c_if	Set a classical equality condition on this instruction between the register or cbit classical and value val.
copy	Copy of the instruction.
inverse	Invert this instruction.
is_parameterized	Return True .IFF.
qasm	Return a default OpenQASM string for the instruction.
repeat	Creates an instruction with gate repeated n amount of times.
replace_blocks	Replace blocks and return new instruction.
reverse_ops	For a composite instruction, reverse the order of sub-instructions.
soft_compare	Soft comparison between gates.
validate_parameter	Instruction parameters has no validation or normalization.

Attributes

blocks

condition_bits

Get Clbits in condition.

Return type

List[Clbit]

decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

definition

Return definition in terms of other basic gates.

duration

Get the duration.

label

Return instruction label

Return type

str

name

Return the name.

num_clbits

Return the number of clbits.

num_qubits

Return the number of qubits.

params

unit

Get the time unit of duration.