268 lines
10 KiB
Plaintext
268 lines
10 KiB
Plaintext
---
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title: MCMTVChain
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description: API reference for qiskit.circuit.library.MCMTVChain
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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.MCMTVChain
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---
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# MCMTVChain
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<Class id="qiskit.circuit.library.MCMTVChain" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.45/qiskit/circuit/library/generalized_gates/mcmt.py" signature="qiskit.circuit.library.MCMTVChain(gate, num_ctrl_qubits, num_target_qubits)" modifiers="class">
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Bases: [`MCMT`](qiskit.circuit.library.MCMT "qiskit.circuit.library.generalized_gates.mcmt.MCMT")
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The MCMT implementation using the CCX V-chain.
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This implementation requires ancillas but is decomposed into a much shallower circuit than the default implementation in [`MCMT`](qiskit.circuit.library.MCMT "qiskit.circuit.library.MCMT").
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**Expanded Circuit:**
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**Examples:**
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> ```python
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> >>> from qiskit.circuit.library import HGate
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> >>> MCMTVChain(HGate(), 3, 2).draw()
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> ```
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>
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> **q\_0: ──■────────────────────────■──**
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>
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> │ │
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>
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> **q\_1: ──■────────────────────────■──**
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>
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> │ │
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>
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> **q\_2: ──┼────■──────────────■────┼──**
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>
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> │ │ ┌───┐ │ │
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>
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> **q\_3: ──┼────┼──┤ H ├───────┼────┼──**
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>
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> │ │ └─┬─┘┌───┐ │ │
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>
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> **q\_4: ──┼────┼────┼──┤ H ├──┼────┼──**
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>
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> ┌─┴─┐ │ │ └─┬─┘ │ ┌─┴─┐
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>
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> **q\_5: ┤ X ├──■────┼────┼────■──┤ X ├**
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>
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> └───┘┌─┴─┐ │ │ ┌─┴─┐└───┘
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>
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> **q\_6: ─────┤ X ├──■────■──┤ X ├─────**
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>
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> └───┘ └───┘
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Create a new multi-control multi-target gate.
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**Parameters**
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* **gate** ([*Gate*](qiskit.circuit.Gate "qiskit.circuit.Gate") *| Callable\[\[*[*QuantumCircuit*](qiskit.circuit.QuantumCircuit "qiskit.circuit.QuantumCircuit")*,* [*Qubit*](qiskit.circuit.Qubit "qiskit.circuit.Qubit")*,* [*Qubit*](qiskit.circuit.Qubit "qiskit.circuit.Qubit")*],* [*circuit.Instruction*](qiskit.circuit.Instruction "qiskit.circuit.Instruction")*]*) – The gate to be applied controlled on the control qubits and applied to the target qubits. Can be either a Gate or a circuit method. If it is a callable, it will be casted to a Gate.
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* **num\_ctrl\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")) – The number of control qubits.
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* **num\_target\_qubits** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")) – The number of target qubits.
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**Raises**
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* [**AttributeError**](https://docs.python.org/3/library/exceptions.html#AttributeError "(in Python v3.12)") – If the gate cannot be casted to a controlled gate.
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* [**AttributeError**](https://docs.python.org/3/library/exceptions.html#AttributeError "(in Python v3.12)") – If the number of controls or targets is 0.
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## Attributes
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### ancillas
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<Attribute id="qiskit.circuit.library.MCMTVChain.ancillas">
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Returns a list of ancilla bits in the order that the registers were added.
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</Attribute>
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### calibrations
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<Attribute id="qiskit.circuit.library.MCMTVChain.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.MCMTVChain.clbits">
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Returns a list of classical bits in the order that the registers were added.
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</Attribute>
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### data
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<Attribute id="qiskit.circuit.library.MCMTVChain.data">
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Return 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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### extension\_lib
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<Attribute id="qiskit.circuit.library.MCMTVChain.extension_lib" attributeValue="'include "qelib1.inc";'" />
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### global\_phase
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<Attribute id="qiskit.circuit.library.MCMTVChain.global_phase">
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Return the global phase of the current circuit scope in radians.
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</Attribute>
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### header
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<Attribute id="qiskit.circuit.library.MCMTVChain.header" attributeValue="'OPENQASM 2.0;'" />
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### instances
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<Attribute id="qiskit.circuit.library.MCMTVChain.instances" attributeValue="182" />
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### layout
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<Attribute id="qiskit.circuit.library.MCMTVChain.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.MCMTVChain.metadata">
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The user provided metadata associated with the circuit.
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The metadata for the circuit is a user provided `dict` of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.
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</Attribute>
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### num\_ancilla\_qubits
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<Attribute id="qiskit.circuit.library.MCMTVChain.num_ancilla_qubits">
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Return the number of ancilla qubits required.
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</Attribute>
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### num\_ancillas
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<Attribute id="qiskit.circuit.library.MCMTVChain.num_ancillas">
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Return the number of ancilla qubits.
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</Attribute>
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### num\_clbits
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<Attribute id="qiskit.circuit.library.MCMTVChain.num_clbits">
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Return number of classical bits.
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</Attribute>
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### num\_parameters
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<Attribute id="qiskit.circuit.library.MCMTVChain.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.MCMTVChain.num_qubits">
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Return number of qubits.
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</Attribute>
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### op\_start\_times
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<Attribute id="qiskit.circuit.library.MCMTVChain.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 v3.12)") – When circuit is not scheduled.
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</Attribute>
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### parameters
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<Attribute id="qiskit.circuit.library.MCMTVChain.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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```
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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.MCMTVChain.prefix" attributeValue="'circuit'" />
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### qubits
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<Attribute id="qiskit.circuit.library.MCMTVChain.qubits">
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Returns a list of quantum bits in the order that the registers were added.
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</Attribute>
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## Methods
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### inverse
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<Function id="qiskit.circuit.library.MCMTVChain.inverse" signature="inverse()">
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Return the inverse MCMT circuit, which is itself.
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</Function>
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</Class>
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