76 lines
4.0 KiB
Plaintext
76 lines
4.0 KiB
Plaintext
---
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title: TwoQubitBasisDecomposer
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description: API reference for qiskit.quantum_info.TwoQubitBasisDecomposer
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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.quantum_info.TwoQubitBasisDecomposer
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---
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# TwoQubitBasisDecomposer
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<Class id="qiskit.quantum_info.TwoQubitBasisDecomposer" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.23/qiskit/quantum_info/synthesis/two_qubit_decompose.py" signature="TwoQubitBasisDecomposer(gate, basis_fidelity=1.0, euler_basis=None, pulse_optimize=None)" modifiers="class">
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Bases: `object`
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A class for decomposing 2-qubit unitaries into minimal number of uses of a 2-qubit basis gate.
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**Parameters**
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* **gate** ([*Gate*](qiskit.circuit.Gate "qiskit.circuit.Gate")) – Two-qubit gate to be used in the KAK decomposition.
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* **basis\_fidelity** (*float*) – Fidelity to be assumed for applications of KAK Gate. Default 1.0.
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* **euler\_basis** (*str*) – Basis string to be provided to OneQubitEulerDecomposer for 1Q synthesis. Valid options are \[‘ZYZ’, ‘ZXZ’, ‘XYX’, ‘U’, ‘U3’, ‘U1X’, ‘PSX’, ‘ZSX’, ‘RR’]. Default ‘U3’.
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* **pulse\_optimize** (*None or bool*) – If True, try to do decomposition which minimizes local unitaries in between entangling gates. This will raise an exception if an optimal decomposition is not implemented. Currently, only \[\{CX, SX, RZ}] is known. If False, don’t attempt optimization. If None, attempt optimization but don’t raise if unknown.
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## Methods
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### decomp0
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<Function id="qiskit.quantum_info.TwoQubitBasisDecomposer.decomp0" signature="TwoQubitBasisDecomposer.decomp0(target)" modifiers="static">
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Decompose target \~Ud(x, y, z) with 0 uses of the basis gate. Result Ur has trace: $|Tr(Ur.Utarget^dag)| = 4|(cos(x)cos(y)cos(z)+ j sin(x)sin(y)sin(z)|$, which is optimal for all targets and bases
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</Function>
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### decomp1
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<Function id="qiskit.quantum_info.TwoQubitBasisDecomposer.decomp1" signature="TwoQubitBasisDecomposer.decomp1(target)">
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Decompose target \~Ud(x, y, z) with 1 uses of the basis gate \~Ud(a, b, c). Result Ur has trace: .. math:
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```python
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|Tr(Ur.Utarget^dag)| = 4|cos(x-a)cos(y-b)cos(z-c) + j sin(x-a)sin(y-b)sin(z-c)|
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```
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which is optimal for all targets and bases with z==0 or c==0
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</Function>
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### decomp2\_supercontrolled
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<Function id="qiskit.quantum_info.TwoQubitBasisDecomposer.decomp2_supercontrolled" signature="TwoQubitBasisDecomposer.decomp2_supercontrolled(target)">
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Decompose target \~Ud(x, y, z) with 2 uses of the basis gate.
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For supercontrolled basis \~Ud(pi/4, b, 0), all b, result Ur has trace .. math:
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```python
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|Tr(Ur.Utarget^dag)| = 4cos(z)
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```
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which is the optimal approximation for basis of CNOT-class `~Ud(pi/4, 0, 0)` or DCNOT-class `~Ud(pi/4, pi/4, 0)` and any target. May be sub-optimal for b!=0 (e.g. there exists exact decomposition for any target using B `B~Ud(pi/4, pi/8, 0)`, but not this decomposition.) This is an exact decomposition for supercontrolled basis and target `~Ud(x, y, 0)`. No guarantees for non-supercontrolled basis.
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</Function>
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### decomp3\_supercontrolled
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<Function id="qiskit.quantum_info.TwoQubitBasisDecomposer.decomp3_supercontrolled" signature="TwoQubitBasisDecomposer.decomp3_supercontrolled(target)">
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Decompose target with 3 uses of the basis. This is an exact decomposition for supercontrolled basis \~Ud(pi/4, b, 0), all b, and any target. No guarantees for non-supercontrolled basis.
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</Function>
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### num\_basis\_gates
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<Function id="qiskit.quantum_info.TwoQubitBasisDecomposer.num_basis_gates" signature="TwoQubitBasisDecomposer.num_basis_gates(unitary)">
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Computes the number of basis gates needed in a decomposition of input unitary
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</Function>
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### traces
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<Function id="qiskit.quantum_info.TwoQubitBasisDecomposer.traces" signature="TwoQubitBasisDecomposer.traces(target)">
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Give the expected traces $|Tr(U \cdot Utarget^dag)|$ for different number of basis gates.
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</Function>
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</Class>
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