297 lines
12 KiB
Plaintext
297 lines
12 KiB
Plaintext
---
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title: UnitaryOverlap (v1.2)
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description: API reference for qiskit.circuit.library.UnitaryOverlap 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.UnitaryOverlap
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---
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# UnitaryOverlap
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<Class id="qiskit.circuit.library.UnitaryOverlap" isDedicatedPage={true} github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/circuit/library/overlap.py#L21-L106" signature="qiskit.circuit.library.UnitaryOverlap(unitary1, unitary2, prefix1='p1', prefix2='p2', insert_barrier=False)" modifiers="class">
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Bases: [`QuantumCircuit`](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.QuantumCircuit")
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Circuit that returns the overlap between two unitaries $U_2^{\dag} U_1$.
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The input quantum circuits must represent unitary operations, since they must be invertible. If the inputs will have parameters, they are replaced by [`ParameterVector`](qiskit.circuit.ParameterVector "qiskit.circuit.ParameterVector")s with names “p1” (for circuit `unitary1`) and “p2” (for circuit `unitary_2`) in the output circuit.
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This circuit is usually employed in computing the fidelity:
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$$
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\left|\langle 0| U_2^{\dag} U_1|0\rangle\right|^{2}
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$$
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by computing the probability of being in the all-zeros bit-string, or equivalently, the expectation value of projector $|0\rangle\langle 0|$.
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Example:
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```python
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import numpy as np
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from qiskit.circuit.library import EfficientSU2, UnitaryOverlap
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from qiskit.primitives import Sampler
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# get two circuit to prepare states of which we comput the overlap
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circuit = EfficientSU2(2, reps=1)
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unitary1 = circuit.assign_parameters(np.random.random(circuit.num_parameters))
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unitary2 = circuit.assign_parameters(np.random.random(circuit.num_parameters))
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# create the overlap circuit
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overlap = UnitaryOverap(unitary1, unitary2)
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# sample from the overlap
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sampler = Sampler(options={"shots": 100})
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result = sampler.run(overlap).result()
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# the fidelity is the probability to measure 0
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fidelity = result.quasi_dists[0].get(0, 0)
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```
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**Parameters**
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* **unitary1** ([*QuantumCircuit*](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.QuantumCircuit")) – Unitary acting on the ket vector.
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* **unitary2** ([*QuantumCircuit*](qiskit.circuit.QuantumCircuit "qiskit.circuit.quantumcircuit.QuantumCircuit")) – Unitary whose inverse operates on the bra vector.
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* **prefix1** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)")) – The name of the parameter vector associated to `unitary1`, if it is parameterized. Defaults to `"p1"`.
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* **prefix2** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)")) – The name of the parameter vector associated to `unitary2`, if it is parameterized. Defaults to `"p2"`.
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* **insert\_barrier** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)")) – Whether to insert a barrier between the two unitaries.
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**Raises**
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* [**CircuitError**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – Number of qubits in `unitary1` and `unitary2` does not match.
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* [**CircuitError**](circuit#qiskit.circuit.CircuitError "qiskit.circuit.CircuitError") – Inputs contain measurements and/or resets.
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## Attributes
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### ancillas
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<Attribute id="qiskit.circuit.library.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.instances" attributeValue="186" />
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### layout
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<Attribute id="qiskit.circuit.library.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.num_input_vars "qiskit.circuit.library.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.num_captured_vars "qiskit.circuit.library.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.num_qubits">
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Return number of qubits.
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</Attribute>
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### num\_vars
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<Attribute id="qiskit.circuit.library.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.prefix" attributeValue="'circuit'" />
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### qubits
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<Attribute id="qiskit.circuit.library.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.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.UnitaryOverlap.unit "qiskit.circuit.library.UnitaryOverlap.unit").
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</Attribute>
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### unit
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<Attribute id="qiskit.circuit.library.UnitaryOverlap.unit">
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The unit that [`duration`](#qiskit.circuit.library.UnitaryOverlap.duration "qiskit.circuit.library.UnitaryOverlap.duration") is specified in.
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</Attribute>
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</Class>
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