50 lines
1.8 KiB
Plaintext
50 lines
1.8 KiB
Plaintext
---
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title: double_commutator
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description: API reference for qiskit.opflow.double_commutator
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in_page_toc_min_heading_level: 1
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python_api_type: function
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python_api_name: qiskit.opflow.double_commutator
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---
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<span id="qiskit-opflow-double-commutator" />
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# qiskit.opflow\.double\_commutator
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<Function id="qiskit.opflow.double_commutator" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.24/qiskit/opflow/utils.py" signature="double_commutator(op_a, op_b, op_c, sign=False)">
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Deprecated: Compute symmetric double commutator of op\_a, op\_b and op\_c. See McWeeny chapter 13.6 Equation of motion methods (page 479)
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If sign is False, it returns
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$$
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[[A, B], C]/2 + [A, [B, C]]/2
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= (2ABC + 2CBA - BAC - CAB - ACB - BCA)/2.
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$$
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If sign is True, it returns
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$$
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\lbrace[A, B], C\rbrace/2 + \lbrace A, [B, C]\rbrace/2
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= (2ABC - 2CBA - BAC + CAB - ACB + BCA)/2.
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$$
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<Admonition title="Deprecated since version 0.24.0" type="danger">
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The function `qiskit.opflow.utils.double_commutator()` is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. For code migration guidelines, visit [https://qisk.it/opflow\_migration](https://qisk.it/opflow_migration).
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</Admonition>
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**Parameters**
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* **op\_a** ([*OperatorBase*](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")) – Operator A
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* **op\_b** ([*OperatorBase*](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")) – Operator B
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* **op\_c** ([*OperatorBase*](qiskit.opflow.OperatorBase "qiskit.opflow.operator_base.OperatorBase")) – Operator C
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* **sign** (*bool*) – False anti-commutes, True commutes
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**Returns**
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the double commutator
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**Return type**
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[OperatorBase](qiskit.opflow.OperatorBase "qiskit.opflow.OperatorBase")
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</Function>
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