Initialize#

class qiskit.extensions.Initialize(params, num_qubits=None, normalize=False)[source]#

Bases: Instruction

Complex amplitude initialization.

Class that initializes some flexible collection of qubit registers, implemented by calling the qiskit.extensions.StatePreparation Class. Note that Initialize is an Instruction and not a Gate since it contains a reset instruction, which is not unitary.

Create new initialize composite.

Parameters:

params (str, list, int or Statevector) --
- Statevector: Statevector to initialize to.
- list: vector of complex amplitudes to initialize to.
- string: labels of basis states of the Pauli eigenstates Z, X, Y. See Statevector.from_label(). Notice the order of the labels is reversed with respect to the qubit index to be applied to. Example label '01' initializes the qubit zero to \(|1\rangle\) and the qubit one to \(|0\rangle\).
- int: an integer that is used as a bitmap indicating which qubits to initialize to \(|1\rangle\). Example: setting params to 5 would initialize qubit 0 and qubit 2 to \(|1\rangle\) and qubit 1 to \(|0\rangle\).
num_qubits (int) -- This parameter is only used if params is an int. Indicates the total number of qubits in the initialize call. Example: initialize covers 5 qubits and params is 3. This allows qubits 0 and 1 to be initialized to \(|1\rangle\) and the remaining 3 qubits to be initialized to \(|0\rangle\).
normalize (bool) -- Whether to normalize an input array to a unit vector.

Attributes

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#: Return initialize params.

unit#: Get the time unit of duration.

Methods

add_decomposition(decomposition)#: Add a decomposition of the instruction to the SessionEquivalenceLibrary.

assemble()#: Assemble a QasmQobjInstruction

broadcast_arguments(qargs, cargs)[source]#

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(classical, val)#: Set a classical equality condition on this instruction between the register or cbit classical and value val.

Note

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(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:: qiskit.circuit.Instruction

gates_to_uncompute()[source]#

Call to create a circuit with gates that take the desired vector to zero.

Returns:: circuit to take self.params vector to \(|{00\ldots0}\rangle\)
Return type:: QuantumCircuit

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:: qiskit.circuit.Instruction
Raises:: CircuitError -- if the instruction is not composite and an inverse has not been implemented for it.

is_parameterized()#: Return True .IFF. instruction is parameterized else False

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];).

Deprecated since version 0.25.0: 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(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:: qiskit.circuit.Instruction
Raises:: CircuitError -- If n < 1.

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:

qiskit.circuit.Instruction

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:: bool

validate_parameter(parameter)#: Instruction parameters has no validation or normalization.