IfElseOp
class qiskit.circuit.IfElseOp(condition, true_body, false_body=None, label=None)
Bases: ControlFlowOp
A circuit operation which executes a program (true_body) if a provided condition (condition) evaluates to true, and optionally evaluates another program (false_body) otherwise.
Parameters
- condition (tuple[ClassicalRegister, int] | tuple[Clbit, int] | expr.Expr) – A condition to be evaluated at circuit runtime which, if true, will trigger the evaluation of
true_body. Can be specified as either a tuple of aClassicalRegisterto be tested for equality with a givenint, or as a tuple of aClbitto be compared to either aboolor anint. - true_body (QuantumCircuit) – A program to be executed if
conditionevaluates to true. - false_body (QuantumCircuit | None) – A optional program to be executed if
conditionevaluates to false. - label (str | None) – An optional label for identifying the instruction.
If provided, false_body must be of the same num_qubits and num_clbits as true_body.
The classical bits used in condition must be a subset of those attached to the circuit on which this IfElseOp will be appended.
Circuit symbol:
┌───────────┐
q_0: ┤0 ├
│ │
q_1: ┤1 ├
│ if_else │
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 orfloat) – instruction’s duration. it must be integer if
unitis ‘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.
Attributes
blocks
condition_bits
Get Clbits in condition.
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
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.
Methods
add_decomposition
add_decomposition(decomposition)
Add a decomposition of the instruction to the SessionEquivalenceLibrary.
assemble
assemble()
Assemble a QasmQobjInstruction
broadcast_arguments
broadcast_arguments(qargs, cargs)
Validation of the arguments.
Parameters
- qargs (List) – List of quantum bit arguments.
- cargs (List) – List of classical bit arguments.
Yields
Tuple(List, List) – A tuple with single arguments.
Raises
CircuitError – If the input is not valid. For example, the number of arguments does not match the gate expectation.
c_if
c_if(classical, val)
Set a classical equality condition on this instruction between the register or cbit classical and value val.
This is a setter method, not an additive one. Calling this multiple times will silently override any previously set condition; it does not stack.
copy
copy(name=None)
Copy of the instruction.
Parameters
name (str) – name to be given to the copied circuit, if None then the name stays the same.
Returns
a copy of the current instruction, with the name updated if it was provided
Return type
inverse
inverse()
Invert this instruction.
If the instruction is composite (i.e. has a definition), then its definition will be recursively inverted.
Special instructions inheriting from Instruction can implement their own inverse (e.g. T and Tdg, Barrier, etc.)
Returns
a fresh instruction for the inverse
Return type
Raises
CircuitError – if the instruction is not composite and an inverse has not been implemented for it.
is_parameterized
is_parameterized()
Return True .IFF. instruction is parameterized else False
qasm
qasm()
Return a default OpenQASM string for the instruction.
Derived instructions may override this to print in a different format (e.g. measure q[0] -> c[0];).
The method qiskit.circuit.instruction.Instruction.qasm() is deprecated as of qiskit-terra 0.25.0. It will be removed no earlier than 3 months after the release date. Correct exporting to OpenQASM 2 is the responsibility of a larger exporter; it cannot safely be done on an object-by-object basis without context. No replacement will be provided, because the premise is wrong.
repeat
repeat(n)
Creates an instruction with gate repeated n amount of times.
Parameters
n (int) – Number of times to repeat the instruction
Returns
Containing the definition.
Return type
Raises
CircuitError – If n < 1.
replace_blocks
replace_blocks(blocks)
Replace blocks and return new instruction.
Parameters
blocks (Iterable[QuantumCircuit]) – Iterable of circuits for “if” and “else” condition. If there is no “else” circuit it may be set to None or omitted.
Returns
New IfElseOp with replaced blocks.
Return type
reverse_ops
reverse_ops()
For a composite instruction, reverse the order of sub-instructions.
This is done by recursively reversing all sub-instructions. It does not invert any gate.
Returns
a new instruction with
sub-instructions reversed.
Return type
soft_compare
soft_compare(other)
Soft comparison between gates. Their names, number of qubits, and classical bit numbers must match. The number of parameters must match. Each parameter is compared. If one is a ParameterExpression then it is not taken into account.
Parameters
other (instruction) – other instruction.
Returns
are self and other equal up to parameter expressions.
Return type
validate_parameter
validate_parameter(parameter)
Instruction parameters has no validation or normalization.