164 lines
6.3 KiB
Plaintext
164 lines
6.3 KiB
Plaintext
---
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title: UCGate (latest version)
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description: API reference for qiskit.circuit.library.UCGate in the latest version of qiskit
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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.UCGate
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---
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# UCGate
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<Class id="qiskit.circuit.library.UCGate" isDedicatedPage={true} github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/library/generalized_gates/uc.py#L42-L213" signature="qiskit.circuit.library.UCGate(gate_list, up_to_diagonal=False)" modifiers="class">
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Bases: [`Gate`](qiskit.circuit.Gate "qiskit.circuit.gate.Gate")
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Uniformly controlled gate (also called multiplexed gate).
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These gates can have several control qubits and a single target qubit. If the k control qubits are in the state $|i\rangle$ (in the computational basis), a single-qubit unitary $U_i$ is applied to the target qubit.
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This gate is represented by a block-diagonal matrix, where each block is a $2\times 2$ unitary, that is
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$$
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\begin{pmatrix}
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U_0 & 0 & \cdots & 0 \\
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0 & U_1 & \cdots & 0 \\
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\vdots & & \ddots & \vdots \\
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0 & 0 & \cdots & U_{2^{k-1}}
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\end{pmatrix}.
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$$
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The decomposition is based on Ref. \[1].
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**References:**
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**\[1] Bergholm et al., Quantum circuits with uniformly controlled one-qubit gates (2005).**
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[Phys. Rev. A 71, 052330](https://journals.aps.org/pra/abstract/10.1103/PhysRevA.71.052330).
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**Parameters**
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* **gate\_list** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")*\[np.ndarray]*) – List of two qubit unitaries $[U_0, ..., U_{2^{k-1}}]$, where each single-qubit unitary $U_i$ is given as a $2 \times 2$ numpy array.
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* **up\_to\_diagonal** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)")) – Determines if the gate is implemented up to a diagonal. or if it is decomposed completely (default: False). If the `UCGate` $U$ is decomposed up to a diagonal $D$, this means that the circuit implements a unitary $U'$ such that $D U' = U$.
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**Raises**
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[**QiskitError**](exceptions#qiskit.exceptions.QiskitError "qiskit.exceptions.QiskitError") – in case of bad input to the constructor
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## Attributes
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### base\_class
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<Attribute id="qiskit.circuit.library.UCGate.base_class">
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Get the base class of this instruction. This is guaranteed to be in the inheritance tree of `self`.
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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`](#qiskit.circuit.library.UCGate.base_class "qiskit.circuit.library.UCGate.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`](qiskit.transpiler.Target "qiskit.transpiler.Target") from the full parametrized gate.
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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:
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```python
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>>> isinstance(XGate(), XGate)
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True
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>>> type(XGate()) is XGate
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False
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>>> XGate().base_class is XGate
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True
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```
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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.
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</Attribute>
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### condition
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<Attribute id="qiskit.circuit.library.UCGate.condition">
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The classical condition on the instruction.
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</Attribute>
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### condition\_bits
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<Attribute id="qiskit.circuit.library.UCGate.condition_bits">
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Get Clbits in condition.
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</Attribute>
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### decompositions
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<Attribute id="qiskit.circuit.library.UCGate.decompositions">
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Get the decompositions of the instruction from the SessionEquivalenceLibrary.
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</Attribute>
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### definition
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<Attribute id="qiskit.circuit.library.UCGate.definition">
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Return definition in terms of other basic gates.
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</Attribute>
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### duration
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<Attribute id="qiskit.circuit.library.UCGate.duration">
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Get the duration.
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</Attribute>
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### label
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<Attribute id="qiskit.circuit.library.UCGate.label">
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Return instruction label
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</Attribute>
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### mutable
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<Attribute id="qiskit.circuit.library.UCGate.mutable">
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Is this instance is a mutable unique instance or not.
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If this attribute is `False` the gate instance is a shared singleton and is not mutable.
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</Attribute>
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### name
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<Attribute id="qiskit.circuit.library.UCGate.name">
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Return the name.
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</Attribute>
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### num\_clbits
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<Attribute id="qiskit.circuit.library.UCGate.num_clbits">
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Return the number of clbits.
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</Attribute>
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### num\_qubits
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<Attribute id="qiskit.circuit.library.UCGate.num_qubits">
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Return the number of qubits.
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</Attribute>
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### params
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<Attribute id="qiskit.circuit.library.UCGate.params">
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The parameters of this `Instruction`. Ideally these will be gate angles.
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</Attribute>
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### unit
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<Attribute id="qiskit.circuit.library.UCGate.unit">
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Get the time unit of duration.
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</Attribute>
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## Methods
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### inverse
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<Function id="qiskit.circuit.library.UCGate.inverse" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/library/generalized_gates/uc.py#L108-L130" signature="inverse(annotated=False)">
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Return the inverse.
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This does not re-compute the decomposition for the multiplexer with the inverse of the gates but simply inverts the existing decomposition.
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**Return type**
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[*Gate*](qiskit.circuit.Gate "qiskit.circuit.gate.Gate")
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</Function>
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### validate\_parameter
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<Function id="qiskit.circuit.library.UCGate.validate_parameter" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/library/generalized_gates/uc.py#L208-L213" signature="validate_parameter(parameter)">
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Uniformly controlled gate parameter has to be an ndarray.
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</Function>
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</Class>
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