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HalfAdderGate

class qiskit.circuit.library.HalfAdderGate(num_state_qubits, label=None)

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Bases: Gate

Compute the sum of two equally-sized qubit registers, including a carry-out bit.

For two registers ∣a⟩n|a\rangle_n and ∣b⟩n|b\rangle_n with nn qubits each, an adder performs the following operation

∣a⟩n∣b⟩n↦∣a⟩n∣a+b⟩n+1.|a\rangle_n |b\rangle_n \mapsto |a\rangle_n |a + b\rangle_{n + 1}.

The quantum register ∣a⟩n|a\rangle_n (and analogously ∣b⟩n|b\rangle_n)

∣a⟩n=∣a0⟩⊗⋯⊗∣an−1⟩,|a\rangle_n = |a_0\rangle \otimes \cdots \otimes |a_{n - 1}\rangle,

for ai∈{0,1}a_i \in \{0, 1\}, is associated with the integer value

a=20a0+21a1+⋯+2n−1an−1.a = 2^{0}a_{0} + 2^{1}a_{1} + \cdots + 2^{n - 1}a_{n - 1}.

Parameters

  • num_state_qubits (int) – The number of qubits in each of the registers.
  • name – The name of the circuit.
  • label (str | None) –

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 behavioral 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 parametrized gate with a particular set of parameters for the purposes of distinguishing it in a Target from the full parametrized 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
True

In 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.

condition

The classical condition on the instruction.

Deprecated since version 1.3.0

The property qiskit.circuit.instruction.Instruction.condition is deprecated as of qiskit 1.3.0. It will be removed in 2.0.0.

condition_bits

Get Clbits in condition.

Deprecated since version 1.3.0

The property qiskit.circuit.instruction.Instruction.condition_bits is deprecated as of qiskit 1.3.0. It will be removed in 2.0.0.

decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

definition

Return definition in terms of other basic gates.

duration

Get the duration.

Deprecated since version 1.3.0

The property qiskit.circuit.instruction.Instruction.duration is deprecated as of qiskit 1.3.0. It will be removed in Qiskit 2.0.0.

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.

num_state_qubits

The number of state qubits, i.e. the number of bits in each input register.

Returns

The number of state qubits.

params

The parameters of this Instruction. Ideally these will be gate angles.

unit

Get the time unit of duration.

Deprecated since version 1.3.0

The property qiskit.circuit.instruction.Instruction.unit is deprecated as of qiskit 1.3.0. It will be removed in Qiskit 2.0.0.

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