393 lines
15 KiB
Plaintext
393 lines
15 KiB
Plaintext
---
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title: CZGate
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description: API reference for qiskit.circuit.library.CZGate
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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.CZGate
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---
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<span id="qiskit-circuit-library-czgate" />
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# qiskit.circuit.library.CZGate
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<Class id="qiskit.circuit.library.CZGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.16/qiskit/circuit/library/standard_gates/z.py" signature="CZGate(label=None, ctrl_state=None)" modifiers="class">
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Controlled-Z gate.
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This is a Clifford and symmetric gate.
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**Circuit symbol:**
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```python
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q_0: ─■─
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│
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q_1: ─■─
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```
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**Matrix representation:**
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$$
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\begin{split}CZ\ q_1, q_0 =
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|0\rangle\langle 0| \otimes I + |1\rangle\langle 1| \otimes Z =
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\begin{pmatrix}
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1 & 0 & 0 & 0 \\
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0 & 1 & 0 & 0 \\
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0 & 0 & 1 & 0 \\
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0 & 0 & 0 & -1
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\end{pmatrix}\end{split}
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$$
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In the computational basis, this gate flips the phase of the target qubit if the control qubit is in the $|1\rangle$ state.
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Create new CZ gate.
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### \_\_init\_\_
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<Function id="qiskit.circuit.library.CZGate.__init__" signature="__init__(label=None, ctrl_state=None)">
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Create new CZ gate.
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</Function>
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## Methods
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| --------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------ |
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| [`__init__`](#qiskit.circuit.library.CZGate.__init__ "qiskit.circuit.library.CZGate.__init__")(\[label, ctrl\_state]) | Create new CZ gate. |
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| [`add_decomposition`](#qiskit.circuit.library.CZGate.add_decomposition "qiskit.circuit.library.CZGate.add_decomposition")(decomposition) | Add a decomposition of the instruction to the SessionEquivalenceLibrary. |
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| [`assemble`](#qiskit.circuit.library.CZGate.assemble "qiskit.circuit.library.CZGate.assemble")() | Assemble a QasmQobjInstruction |
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| [`broadcast_arguments`](#qiskit.circuit.library.CZGate.broadcast_arguments "qiskit.circuit.library.CZGate.broadcast_arguments")(qargs, cargs) | Validation and handling of the arguments and its relationship. |
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| [`c_if`](#qiskit.circuit.library.CZGate.c_if "qiskit.circuit.library.CZGate.c_if")(classical, val) | Add classical condition on register classical and value val. |
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| [`control`](#qiskit.circuit.library.CZGate.control "qiskit.circuit.library.CZGate.control")(\[num\_ctrl\_qubits, label, ctrl\_state]) | Return controlled version of gate. |
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| [`copy`](#qiskit.circuit.library.CZGate.copy "qiskit.circuit.library.CZGate.copy")(\[name]) | Copy of the instruction. |
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| [`inverse`](#qiskit.circuit.library.CZGate.inverse "qiskit.circuit.library.CZGate.inverse")() | Return inverted CZ gate (itself). |
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| [`is_parameterized`](#qiskit.circuit.library.CZGate.is_parameterized "qiskit.circuit.library.CZGate.is_parameterized")() | Return True .IFF. |
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| [`mirror`](#qiskit.circuit.library.CZGate.mirror "qiskit.circuit.library.CZGate.mirror")() | DEPRECATED: use instruction.reverse\_ops(). |
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| [`power`](#qiskit.circuit.library.CZGate.power "qiskit.circuit.library.CZGate.power")(exponent) | Creates a unitary gate as gate^exponent. |
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| [`qasm`](#qiskit.circuit.library.CZGate.qasm "qiskit.circuit.library.CZGate.qasm")() | Return a default OpenQASM string for the instruction. |
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| [`repeat`](#qiskit.circuit.library.CZGate.repeat "qiskit.circuit.library.CZGate.repeat")(n) | Creates an instruction with gate repeated n amount of times. |
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| [`reverse_ops`](#qiskit.circuit.library.CZGate.reverse_ops "qiskit.circuit.library.CZGate.reverse_ops")() | For a composite instruction, reverse the order of sub-instructions. |
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| [`to_matrix`](#qiskit.circuit.library.CZGate.to_matrix "qiskit.circuit.library.CZGate.to_matrix")() | Return a numpy.array for the CZ gate. |
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| [`validate_parameter`](#qiskit.circuit.library.CZGate.validate_parameter "qiskit.circuit.library.CZGate.validate_parameter")(parameter) | Gate parameters should be int, float, or ParameterExpression |
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## Attributes
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| ------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------- |
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| [`ctrl_state`](#qiskit.circuit.library.CZGate.ctrl_state "qiskit.circuit.library.CZGate.ctrl_state") | Return the control state of the gate as a decimal integer. |
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| [`decompositions`](#qiskit.circuit.library.CZGate.decompositions "qiskit.circuit.library.CZGate.decompositions") | Get the decompositions of the instruction from the SessionEquivalenceLibrary. |
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| [`definition`](#qiskit.circuit.library.CZGate.definition "qiskit.circuit.library.CZGate.definition") | Return definition in terms of other basic gates. |
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| [`duration`](#qiskit.circuit.library.CZGate.duration "qiskit.circuit.library.CZGate.duration") | Get the duration. |
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| [`label`](#qiskit.circuit.library.CZGate.label "qiskit.circuit.library.CZGate.label") | Return gate label |
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| [`num_ctrl_qubits`](#qiskit.circuit.library.CZGate.num_ctrl_qubits "qiskit.circuit.library.CZGate.num_ctrl_qubits") | Get number of control qubits. |
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| [`params`](#qiskit.circuit.library.CZGate.params "qiskit.circuit.library.CZGate.params") | Get parameters from base\_gate. |
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| [`unit`](#qiskit.circuit.library.CZGate.unit "qiskit.circuit.library.CZGate.unit") | Get the time unit of duration. |
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### add\_decomposition
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<Function id="qiskit.circuit.library.CZGate.add_decomposition" signature="add_decomposition(decomposition)">
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Add a decomposition of the instruction to the SessionEquivalenceLibrary.
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</Function>
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### assemble
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<Function id="qiskit.circuit.library.CZGate.assemble" signature="assemble()">
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Assemble a QasmQobjInstruction
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**Return type**
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`Instruction`
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</Function>
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### broadcast\_arguments
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<Function id="qiskit.circuit.library.CZGate.broadcast_arguments" signature="broadcast_arguments(qargs, cargs)">
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Validation and handling of the arguments and its relationship.
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For example, `cx([q[0],q[1]], q[2])` means `cx(q[0], q[2]); cx(q[1], q[2])`. This method yields the arguments in the right grouping. In the given example:
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```python
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in: [[q[0],q[1]], q[2]],[]
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outs: [q[0], q[2]], []
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[q[1], q[2]], []
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```
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The general broadcasting rules are:
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> * If len(qargs) == 1:
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>
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> ```python
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> [q[0], q[1]] -> [q[0]],[q[1]]
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> ```
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>
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> * If len(qargs) == 2:
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>
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> ```python
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> [[q[0], q[1]], [r[0], r[1]]] -> [q[0], r[0]], [q[1], r[1]]
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> [[q[0]], [r[0], r[1]]] -> [q[0], r[0]], [q[0], r[1]]
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> [[q[0], q[1]], [r[0]]] -> [q[0], r[0]], [q[1], r[0]]
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> ```
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>
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> * If len(qargs) >= 3:
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>
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> ```python
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> [q[0], q[1]], [r[0], r[1]], ...] -> [q[0], r[0], ...], [q[1], r[1], ...]
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> ```
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**Parameters**
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* **qargs** (`List`) – List of quantum bit arguments.
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* **cargs** (`List`) – List of classical bit arguments.
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**Return type**
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`Tuple`\[`List`, `List`]
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**Returns**
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A tuple with single arguments.
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**Raises**
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**CircuitError** – If the input is not valid. For example, the number of arguments does not match the gate expectation.
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</Function>
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### c\_if
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<Function id="qiskit.circuit.library.CZGate.c_if" signature="c_if(classical, val)">
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Add classical condition on register classical and value val.
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</Function>
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### control
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<Function id="qiskit.circuit.library.CZGate.control" signature="control(num_ctrl_qubits=1, label=None, ctrl_state=None)">
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Return controlled version of gate. See [`ControlledGate`](qiskit.circuit.ControlledGate "qiskit.circuit.ControlledGate") for usage.
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**Parameters**
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* **num\_ctrl\_qubits** (`Optional`\[`int`]) – number of controls to add to gate (default=1)
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* **label** (`Optional`\[`str`]) – optional gate label
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* **ctrl\_state** (`Union`\[`int`, `str`, `None`]) – The control state in decimal or as a bitstring (e.g. ‘111’). If None, use 2\*\*num\_ctrl\_qubits-1.
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**Returns**
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Controlled version of gate. This default algorithm uses num\_ctrl\_qubits-1 ancillae qubits so returns a gate of size num\_qubits + 2\*num\_ctrl\_qubits - 1.
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**Return type**
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[qiskit.circuit.ControlledGate](qiskit.circuit.ControlledGate "qiskit.circuit.ControlledGate")
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**Raises**
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**QiskitError** – unrecognized mode or invalid ctrl\_state
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</Function>
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### copy
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<Function id="qiskit.circuit.library.CZGate.copy" signature="copy(name=None)">
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Copy of the instruction.
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**Parameters**
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**name** (*str*) – name to be given to the copied circuit, if None then the name stays the same.
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**Returns**
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**a copy of the current instruction, with the name**
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updated if it was provided
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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</Function>
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### ctrl\_state
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<Attribute id="qiskit.circuit.library.CZGate.ctrl_state">
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Return the control state of the gate as a decimal integer.
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**Return type**
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`int`
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</Attribute>
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### decompositions
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<Attribute id="qiskit.circuit.library.CZGate.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.CZGate.definition">
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Return definition in terms of other basic gates. If the gate has open controls, as determined from self.ctrl\_state, the returned definition is conjugated with X without changing the internal \_definition.
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**Return type**
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`List`
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</Attribute>
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### duration
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<Attribute id="qiskit.circuit.library.CZGate.duration">
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Get the duration.
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</Attribute>
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### inverse
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<Function id="qiskit.circuit.library.CZGate.inverse" signature="inverse()">
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Return inverted CZ gate (itself).
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</Function>
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### is\_parameterized
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<Function id="qiskit.circuit.library.CZGate.is_parameterized" signature="is_parameterized()">
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Return True .IFF. instruction is parameterized else False
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</Function>
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### label
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<Attribute id="qiskit.circuit.library.CZGate.label">
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Return gate label
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**Return type**
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`str`
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</Attribute>
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### mirror
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<Function id="qiskit.circuit.library.CZGate.mirror" signature="mirror()">
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DEPRECATED: use instruction.reverse\_ops().
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**Returns**
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**a new instruction with sub-instructions**
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reversed.
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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</Function>
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### num\_ctrl\_qubits
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<Attribute id="qiskit.circuit.library.CZGate.num_ctrl_qubits">
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Get number of control qubits.
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**Returns**
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The number of control qubits for the gate.
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**Return type**
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int
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</Attribute>
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### params
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<Attribute id="qiskit.circuit.library.CZGate.params">
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Get parameters from base\_gate.
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**Returns**
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List of gate parameters.
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**Return type**
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list
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**Raises**
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**CircuitError** – Controlled gate does not define a base gate
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</Attribute>
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### power
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<Function id="qiskit.circuit.library.CZGate.power" signature="power(exponent)">
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Creates a unitary gate as gate^exponent.
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**Parameters**
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**exponent** (*float*) – Gate^exponent
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**Returns**
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To which to\_matrix is self.to\_matrix^exponent.
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**Return type**
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[qiskit.extensions.UnitaryGate](qiskit.extensions.UnitaryGate "qiskit.extensions.UnitaryGate")
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**Raises**
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**CircuitError** – If Gate is not unitary
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</Function>
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### qasm
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<Function id="qiskit.circuit.library.CZGate.qasm" signature="qasm()">
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Return a default OpenQASM string for the instruction.
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Derived instructions may override this to print in a different format (e.g. measure q\[0] -> c\[0];).
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</Function>
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### repeat
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<Function id="qiskit.circuit.library.CZGate.repeat" signature="repeat(n)">
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Creates an instruction with gate repeated n amount of times.
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**Parameters**
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**n** (*int*) – Number of times to repeat the instruction
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**Returns**
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Containing the definition.
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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**Raises**
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**CircuitError** – If n \< 1.
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</Function>
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### reverse\_ops
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<Function id="qiskit.circuit.library.CZGate.reverse_ops" signature="reverse_ops()">
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For a composite instruction, reverse the order of sub-instructions.
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This is done by recursively reversing all sub-instructions. It does not invert any gate.
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**Returns**
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**a new instruction with**
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sub-instructions reversed.
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**Return type**
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[qiskit.circuit.Instruction](qiskit.circuit.Instruction "qiskit.circuit.Instruction")
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</Function>
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### to\_matrix
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<Function id="qiskit.circuit.library.CZGate.to_matrix" signature="to_matrix()">
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Return a numpy.array for the CZ gate.
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</Function>
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### unit
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<Attribute id="qiskit.circuit.library.CZGate.unit">
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Get the time unit of duration.
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</Attribute>
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### validate\_parameter
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<Function id="qiskit.circuit.library.CZGate.validate_parameter" signature="validate_parameter(parameter)">
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Gate parameters should be int, float, or ParameterExpression
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</Function>
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</Class>
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