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Initialize

class Initialize(params, num_qubits=None)

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Bases: qiskit.circuit.instruction.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|1\rangle and the qubit one to 0|0\rangle.
    • int: an integer that is used as a bitmap indicating which qubits to initialize to 1|1\rangle. Example: setting params to 5 would initialize qubit 0 and qubit 2 to 1|1\rangle and qubit 1 to 0|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|1\rangle and the remaining 3 qubits to be initialized to 0|0\rangle.


Methods

add_decomposition

Initialize.add_decomposition(decomposition)

Add a decomposition of the instruction to the SessionEquivalenceLibrary.

assemble

Initialize.assemble()

Assemble a QasmQobjInstruction

broadcast_arguments

Initialize.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

Initialize.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

Initialize.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

Initialize.gates_to_uncompute()

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

Returns

circuit to take self.params vector to 000|{00\ldots0}\rangle

Return type

QuantumCircuit

inverse

Initialize.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

Initialize.is_parameterized()

Return True .IFF. instruction is parameterized else False

qasm

Initialize.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];).

repeat

Initialize.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

Initialize.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

Initialize.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

Initialize.validate_parameter(parameter)

Instruction parameters has no validation or normalization.


Attributes

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

Return initialize params.

unit

Get the time unit of duration.

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