SwitchCaseOp
class qiskit.circuit.SwitchCaseOp(target, cases, *, label=None)
Bases: ControlFlowOp
A circuit operation that executes one particular circuit block based on matching a given target against an ordered list of values. The special value CASE_DEFAULT can be used to represent a default condition.
This is the low-level interface for creating a switch-case statement; in general, the circuit method QuantumCircuit.switch() should be used as a context manager to access the builder interface. At the low level, you must ensure that all the circuit blocks contain equal numbers of qubits and clbits, and that the order the virtual bits of the containing circuit should be bound is the same for all blocks. This will likely mean that each circuit block is wider than its natural width, as each block must span the union of all the spaces covered by any of the blocks.
Parameters
- target (Clbit |ClassicalRegister |expr.Expr) – the runtime value to switch on.
- cases (Iterable[Tuple[Any, QuantumCircuit]]) – an ordered iterable of the corresponding value of the
targetand the circuit block that should be executed if this is matched. There is no fall-through between blocks, and the order matters.
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
base_class
Get the base class of this instruction. This is guaranteed to be in the inheritance tree of self.
The “base class” of an instruction is the lowest class in its inheritance tree that the object should be considered entirely compatible with for _all_ circuit applications. This typically means that the subclass is defined purely to offer some sort of programmer convenience over the base class, and the base class is the “true” class for a behavioural perspective. In particular, you should not override base_class if you are defining a custom version of an instruction that will be implemented differently by hardware, such as an alternative measurement strategy, or a version of a parametrised gate with a particular set of parameters for the purposes of distinguishing it in a Target from the full parametrised gate.
This is often exactly equivalent to type(obj), except in the case of singleton instances of standard-library instructions. These singleton instances are special subclasses of their base class, and this property will return that base. For example:
>>> isinstance(XGate(), XGate)
True
>>> type(XGate()) is XGate
False
>>> XGate().base_class is XGate
TrueIn general, you should not rely on the precise class of an instruction; within a given circuit, it is expected that Instruction.name should be a more suitable discriminator in most situations.
blocks
condition
The classical condition on the instruction.
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
mutable
Is this instance is a mutable unique instance or not.
If this attribute is False the gate instance is a shared singleton and is not mutable.
name
Return the name.
num_clbits
Return the number of clbits.
num_qubits
Return the number of qubits.
params
return instruction 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.
cases
cases()
Return a lookup table from case labels to the circuit that would be executed in that case. This object is not generally suitable for creating a new SwitchCaseOp because any keys that point to the same object will not be grouped.
SwitchCaseOp.cases_specifier()
An alternate method that produces its output in a suitable format for creating new SwitchCaseOp instances.
cases_specifier
cases_specifier()
Return an iterable where each element is a 2-tuple whose first element is a tuple of jump values, and whose second is the single circuit block that is associated with those values.
This is an abstract specification of the jump table suitable for creating new SwitchCaseOp instances.
Create a lookup table that you can use for your own purposes to jump from values to the circuit that would be executed.
Return type
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 in the Qiskit 1.0 release. 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 self repeated :math`n` times.
If this operation has a conditional, the output instruction will have the same conditional and the inner repeated operations will be unconditional; instructions within a compound definition cannot be conditioned on registers within Qiskit’s data model. This means that it is not valid to apply a repeated instruction to a clbit that it both writes to and reads from in its condition.
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. :param blocks: Tuple of QuantumCircuits to replace in instruction.
Returns
New ControlFlowOp 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
to_mutable
to_mutable()
Return a mutable copy of this gate.
This method will return a new mutable copy of this gate instance. If a singleton instance is being used this will be a new unique instance that can be mutated. If the instance is already mutable it will be a deepcopy of that instance.
validate_parameter
validate_parameter(parameter)
Instruction parameters has no validation or normalization.