297 lines
13 KiB
Plaintext
297 lines
13 KiB
Plaintext
---
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title: VBERippleCarryAdder (v1.2)
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description: API reference for qiskit.circuit.library.VBERippleCarryAdder in qiskit v1.2
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in_page_toc_min_heading_level: 1
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python_api_type: class
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python_api_name: qiskit.circuit.library.VBERippleCarryAdder
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---
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# VBERippleCarryAdder
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<Class id="qiskit.circuit.library.VBERippleCarryAdder" isDedicatedPage={true} github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/library/arithmetic/adders/vbe_ripple_carry_adder.py#L22-L165" signature="qiskit.circuit.library.VBERippleCarryAdder(num_state_qubits, kind='full', name='VBERippleCarryAdder')" modifiers="class">
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Bases: `Adder`
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The VBE ripple carry adder \[1].
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This circuit performs inplace addition of two equally-sized quantum registers. As an example, a classical adder circuit that performs full addition (i.e. including a carry-in bit) on two 2-qubit sized registers is as follows:
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```python
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┌────────┐ ┌───────────┐┌──────┐
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cin_0: ┤0 ├───────────────────────┤0 ├┤0 ├
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│ │ │ ││ │
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a_0: ┤1 ├───────────────────────┤1 ├┤1 ├
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│ │┌────────┐ ┌──────┐│ ││ Sum │
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a_1: ┤ ├┤1 ├──■──┤1 ├┤ ├┤ ├
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│ ││ │ │ │ ││ ││ │
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b_0: ┤2 Carry ├┤ ├──┼──┤ ├┤2 Carry_dg ├┤2 ├
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│ ││ │┌─┴─┐│ ││ │└──────┘
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b_1: ┤ ├┤2 Carry ├┤ X ├┤2 Sum ├┤ ├────────
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│ ││ │└───┘│ ││ │
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cout_0: ┤ ├┤3 ├─────┤ ├┤ ├────────
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│ ││ │ │ ││ │
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helper_0: ┤3 ├┤0 ├─────┤0 ├┤3 ├────────
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└────────┘└────────┘ └──────┘└───────────┘
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```
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Here *Carry* and *Sum* gates correspond to the gates introduced in \[1]. *Carry\_dg* correspond to the inverse of the *Carry* gate. Note that in this implementation the input register qubits are ordered as all qubits from the first input register, followed by all qubits from the second input register. This is different ordering as compared to Figure 2 in \[1], which leads to a different drawing of the circuit.
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**References:**
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\[1] Vedral et al., Quantum Networks for Elementary Arithmetic Operations, 1995. [arXiv:quant-ph/9511018](https://arxiv.org/pdf/quant-ph/9511018.pdf)
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**Parameters**
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* **num\_state\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)")) – The size of the register.
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* **kind** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)")) – The kind of adder, can be `'full'` for a full adder, `'half'` for a half adder, or `'fixed'` for a fixed-sized adder. A full adder includes both carry-in and carry-out, a half only carry-out, and a fixed-sized adder neither carry-in nor carry-out.
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* **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)")) – The name of the circuit.
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**Raises**
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[**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError "(in Python v3.13)") – If `num_state_qubits` is lower than 1.
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## Attributes
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### ancillas
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.ancillas">
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A list of `AncillaQubit`s in the order that they were added. You should not mutate this.
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</Attribute>
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### calibrations
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.calibrations">
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Return calibration dictionary.
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The custom pulse definition of a given gate is of the form `{'gate_name': {(qubits, params): schedule}}`
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</Attribute>
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### clbits
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.clbits">
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A list of `Clbit`s in the order that they were added. You should not mutate this.
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</Attribute>
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### data
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.data">
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The circuit data (instructions and context).
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**Returns**
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a list-like object containing the [`CircuitInstruction`](qiskit.circuit.CircuitInstruction "qiskit.circuit.CircuitInstruction")s for each instruction.
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**Return type**
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QuantumCircuitData
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</Attribute>
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### global\_phase
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.global_phase">
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The global phase of the current circuit scope in radians.
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</Attribute>
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### instances
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.instances" attributeValue="160" />
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### layout
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.layout">
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Return any associated layout information about the circuit
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This attribute contains an optional [`TranspileLayout`](qiskit.transpiler.TranspileLayout "qiskit.transpiler.TranspileLayout") object. This is typically set on the output from [`transpile()`](compiler#qiskit.compiler.transpile "qiskit.compiler.transpile") or [`PassManager.run()`](qiskit.transpiler.PassManager#run "qiskit.transpiler.PassManager.run") to retain information about the permutations caused on the input circuit by transpilation.
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There are two types of permutations caused by the [`transpile()`](compiler#qiskit.compiler.transpile "qiskit.compiler.transpile") function, an initial layout which permutes the qubits based on the selected physical qubits on the [`Target`](qiskit.transpiler.Target "qiskit.transpiler.Target"), and a final layout which is an output permutation caused by [`SwapGate`](qiskit.circuit.library.SwapGate "qiskit.circuit.library.SwapGate")s inserted during routing.
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</Attribute>
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### metadata
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.metadata">
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Arbitrary user-defined metadata for the circuit.
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Qiskit will not examine the content of this mapping, but it will pass it through the transpiler and reattach it to the output, so you can track your own metadata.
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</Attribute>
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### num\_ancillas
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_ancillas">
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Return the number of ancilla qubits.
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</Attribute>
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### num\_captured\_vars
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_captured_vars">
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The number of real-time classical variables in the circuit marked as captured from an enclosing scope.
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This is the length of the `iter_captured_vars()` iterable. If this is non-zero, [`num_input_vars`](#qiskit.circuit.library.VBERippleCarryAdder.num_input_vars "qiskit.circuit.library.VBERippleCarryAdder.num_input_vars") must be zero.
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</Attribute>
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### num\_clbits
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_clbits">
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Return number of classical bits.
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</Attribute>
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### num\_declared\_vars
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_declared_vars">
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The number of real-time classical variables in the circuit that are declared by this circuit scope, excluding inputs or captures.
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This is the length of the `iter_declared_vars()` iterable.
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</Attribute>
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### num\_input\_vars
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_input_vars">
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The number of real-time classical variables in the circuit marked as circuit inputs.
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This is the length of the `iter_input_vars()` iterable. If this is non-zero, [`num_captured_vars`](#qiskit.circuit.library.VBERippleCarryAdder.num_captured_vars "qiskit.circuit.library.VBERippleCarryAdder.num_captured_vars") must be zero.
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</Attribute>
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### num\_parameters
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_parameters">
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The number of parameter objects in the circuit.
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</Attribute>
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### num\_qubits
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_qubits">
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Return number of qubits.
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</Attribute>
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### num\_state\_qubits
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_state_qubits">
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The number of state qubits, i.e. the number of bits in each input register.
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**Returns**
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The number of state qubits.
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</Attribute>
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### num\_vars
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.num_vars">
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The number of real-time classical variables in the circuit.
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This is the length of the `iter_vars()` iterable.
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</Attribute>
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### op\_start\_times
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.op_start_times">
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Return a list of operation start times.
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This attribute is enabled once one of scheduling analysis passes runs on the quantum circuit.
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**Returns**
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List of integers representing instruction start times. The index corresponds to the index of instruction in `QuantumCircuit.data`.
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**Raises**
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[**AttributeError**](https://docs.python.org/3/library/exceptions.html#AttributeError "(in Python v3.13)") – When circuit is not scheduled.
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</Attribute>
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### parameters
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.parameters">
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The parameters defined in the circuit.
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This attribute returns the [`Parameter`](qiskit.circuit.Parameter "qiskit.circuit.Parameter") objects in the circuit sorted alphabetically. Note that parameters instantiated with a [`ParameterVector`](qiskit.circuit.ParameterVector "qiskit.circuit.ParameterVector") are still sorted numerically.
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**Examples**
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The snippet below shows that insertion order of parameters does not matter.
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```python
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>>> from qiskit.circuit import QuantumCircuit, Parameter
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>>> a, b, elephant = Parameter("a"), Parameter("b"), Parameter("elephant")
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>>> circuit = QuantumCircuit(1)
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>>> circuit.rx(b, 0)
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>>> circuit.rz(elephant, 0)
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>>> circuit.ry(a, 0)
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>>> circuit.parameters # sorted alphabetically!
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ParameterView([Parameter(a), Parameter(b), Parameter(elephant)])
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```
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Bear in mind that alphabetical sorting might be unintuitive when it comes to numbers. The literal “10” comes before “2” in strict alphabetical sorting.
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```python
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>>> from qiskit.circuit import QuantumCircuit, Parameter
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>>> angles = [Parameter("angle_1"), Parameter("angle_2"), Parameter("angle_10")]
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>>> circuit = QuantumCircuit(1)
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>>> circuit.u(*angles, 0)
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>>> circuit.draw()
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┌─────────────────────────────┐
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q: ┤ U(angle_1,angle_2,angle_10) ├
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└─────────────────────────────┘
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>>> circuit.parameters
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ParameterView([Parameter(angle_1), Parameter(angle_10), Parameter(angle_2)])
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```
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To respect numerical sorting, a [`ParameterVector`](qiskit.circuit.ParameterVector "qiskit.circuit.ParameterVector") can be used.
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```python
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>>> from qiskit.circuit import QuantumCircuit, Parameter, ParameterVector
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>>> x = ParameterVector("x", 12)
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>>> circuit = QuantumCircuit(1)
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>>> for x_i in x:
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... circuit.rx(x_i, 0)
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>>> circuit.parameters
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ParameterView([
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ParameterVectorElement(x[0]), ParameterVectorElement(x[1]),
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ParameterVectorElement(x[2]), ParameterVectorElement(x[3]),
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..., ParameterVectorElement(x[11])
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])
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```
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**Returns**
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The sorted [`Parameter`](qiskit.circuit.Parameter "qiskit.circuit.Parameter") objects in the circuit.
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</Attribute>
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### prefix
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.prefix" attributeValue="'circuit'" />
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### qubits
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.qubits">
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A list of `Qubit`s in the order that they were added. You should not mutate this.
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</Attribute>
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### name
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.name" attributeTypeHint="str">
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A human-readable name for the circuit.
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</Attribute>
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### qregs
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.qregs" attributeTypeHint="list[QuantumRegister]">
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A list of the `QuantumRegister`s in this circuit. You should not mutate this.
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</Attribute>
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### cregs
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.cregs" attributeTypeHint="list[ClassicalRegister]">
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A list of the `ClassicalRegister`s in this circuit. You should not mutate this.
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</Attribute>
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### duration
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.duration" attributeTypeHint="int | float | None">
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The total duration of the circuit, set by a scheduling transpiler pass. Its unit is specified by [`unit`](#qiskit.circuit.library.VBERippleCarryAdder.unit "qiskit.circuit.library.VBERippleCarryAdder.unit").
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</Attribute>
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### unit
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<Attribute id="qiskit.circuit.library.VBERippleCarryAdder.unit">
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The unit that [`duration`](#qiskit.circuit.library.VBERippleCarryAdder.duration "qiskit.circuit.library.VBERippleCarryAdder.duration") is specified in.
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</Attribute>
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</Class>
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