qml.qchem.qubit_observable¶
- qubit_observable(o_ferm, cutoff=1e-12, mapping='jordan_wigner')[source]¶
Convert a fermionic observable to a PennyLane qubit observable.
- Parameters
o_ferm (Union[FermiWord, FermiSentence]) – fermionic operator
cutoff (float) – cutoff value for discarding the negligible terms
mapping (str) – Specifies the fermion-to-qubit mapping. Input values can be
'jordan_wigner'
,'parity'
or'bravyi_kitaev'
.
- Returns
Simplified PennyLane Hamiltonian
- Return type
Example
>>> w1 = qml.fermi.FermiWord({(0, 0) : '+', (1, 1) : '-'}) >>> w2 = qml.fermi.FermiWord({(0, 0) : '+', (1, 1) : '-'}) >>> s = qml.fermi.FermiSentence({w1 : 1.2, w2: 3.1}) >>> print(qubit_observable(s)) -0.775j * (Y(0) @ X(1)) + 0.775 * (Y(0) @ Y(1)) + 0.775 * (X(0) @ X(1)) + 0.775j * (X(0) @ Y(1))
If the new op-math is deactivated, a legacy
Hamiltonian
instance is returned.>>> qml.operation.disable_new_opmath() UserWarning: Disabling the new Operator arithmetic system for legacy support. If you need help troubleshooting your code, please visit https://docs.pennylane.ai/en/stable/news/new_opmath.html >>> w1 = qml.fermi.FermiWord({(0, 0) : '+', (1, 1) : '-'}) >>> w2 = qml.fermi.FermiWord({(0, 1) : '+', (1, 2) : '-'}) >>> s = qml.fermi.FermiSentence({w1 : 1.2, w2: 3.1}) >>> print(qubit_observable(s)) (-0.3j) [Y0 X1] + (0.3j) [X0 Y1] + (-0.775j) [Y1 X2] + (0.775j) [X1 Y2] + ((0.3+0j)) [Y0 Y1] + ((0.3+0j)) [X0 X1] + ((0.775+0j)) [Y1 Y2] + ((0.775+0j)) [X1 X2]
code/api/pennylane.qchem.qubit_observable
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