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BasicAer (and Aer) do not capture global phase #4805

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Cryoris opened this issue Jul 26, 2020 · 1 comment · Fixed by #4915
Closed

BasicAer (and Aer) do not capture global phase #4805

Cryoris opened this issue Jul 26, 2020 · 1 comment · Fixed by #4915
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bug Something isn't working

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@Cryoris
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Cryoris commented Jul 26, 2020

Information

  • Qiskit Terra version: 8f717d9
  • Python version: 3.7.7
  • Operating system: macOS Catalina

What is the current behavior?

BasicAer doesn't get the phases right (neither does Aer, but that'll probably be fixed within Aer). The tests using BasicAer, which I think is only test_to_matrix in test_extensions_standard works by coincidence because the rotation angles are 0 and thereby the phase difference is e^{i0} = 1.

Also this causes the tests in #4638 to fail, because there's a test using BasicAer where the phase is not 1.

Steps to reproduce the problem

>>> qc = QuantumCircuit(1)
>>> qc.rz(0.2, 0)
>>> Operator(qc)
Operator([[0.99500417-0.09983342j, 0.        +0.j        ],
          [0.        +0.j        , 0.99500417+0.09983342j]],
         input_dims=(2,), output_dims=(2,))
>>> execute(qc, Aer.get_backend('unitary_simulator')).result().get_unitary()
array([[1.        +0.j        , 0.        +0.j        ],
       [0.        +0.j        , 0.98006658+0.19866933j]])
>>> execute(qc, BasicAer.get_backend('unitary_simulator')).result().get_unitary()
array([[1.        +0.j        , 0.        +0.j        ],
       [0.        +0.j        , 0.98006658+0.19866933j]])
@Cryoris Cryoris added the bug Something isn't working label Jul 26, 2020
@Cryoris Cryoris mentioned this issue Jul 26, 2020
Merged
@kdk kdk added this to the 0.15 milestone Jul 28, 2020
@Cryoris Cryoris mentioned this issue Jul 28, 2020
Closed
@mtreinish mtreinish mentioned this issue Jul 29, 2020
Merged
mtreinish added a commit to mtreinish/qiskit-core that referenced this issue Jul 29, 2020
@mtreinish
Add global phase to qobj in assembly
4a4d36b 
This commit adds the global phase circuit property to the experiment
headers in the assembled qobj. Currently we do not pass the global phase
to backends so simulators can not take it into account. The experiment
header is used since it's a free form field for properties of the
circuit that a backend can use if they want, but there are no
requirements on it. With this in place it should enable Qiskit#4805 and
Qiskit/qiskit-aer#847 to be fixed.

Related to Qiskit#4805
mtreinish added a commit that referenced this issue Jul 29, 2020
@mtreinish
Add global phase to qobj in assembly (#4822)
3c039db 
This commit adds the global phase circuit property to the experiment
headers in the assembled qobj. Currently we do not pass the global phase
to backends so simulators can not take it into account. The experiment
header is used since it's a free form field for properties of the
circuit that a backend can use if they want, but there are no
requirements on it. With this in place it should enable #4805 and
Qiskit/qiskit-aer#847 to be fixed.

Related to #4805
@kdk kdk modified the milestones: 0.15, 0.16 Aug 4, 2020
@ewinston ewinston mentioned this issue Aug 12, 2020
Merged
@chriseclectic
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Qobj global phase support was added to Aer in Qiskit/qiskit-aer#931

@mergify mergify bot closed this as completed in #4915 Sep 24, 2020
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basicaer handling of global_phase. ewinston/qiskit
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@chriseclectic @kdk @Cryoris