FullAncillaAllocation for backends witout a coupling map #10240
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eggerdj
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Pull Request Test Coverage Report for Build 5222217308
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| @@ -85,6 +85,11 @@ def run(self, dag): | |||
| idle_physical_qubits = [ | |||
| q for q in self.coupling_map.physical_qubits if q not in physical_bits | |||
| ] | |||
| else: | |||
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Seems like this branching causes an edge case. When you partly define two qubit gate on your system it will give you imperfect coupling map and you cannot expand the single qubit experiment circuit as you expect. This if-clause should be conditioned on target.
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@nkanazawa1989 can you make a suggestion?
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I meant
if self.target:
idle_physical_qubits = [
q for q in range(self.target.num_qubits) if q not in physical_bits
]
elif self.coupling_map:
idle_physical_qubits = [
q for q in self.coupling_map.physical_qubits if q not in physical_bits
]
else:
raise SomeErrorBy doing this you can always expand circuit to full physical qubits widths.
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As discussed, see change here: f5350b5
mtreinish
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Jun 8, 2023
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Co-authored-by: Matthew Treinish <mtreinish@kortar.org>
mtreinish
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Jun 9, 2023
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Changelog: Bugfix
thspreetham98
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Jun 19, 2023
* * Added support for targets without a coupling map. * * Removed restrictive raise. * * Changed order of target and coupling map * Apply suggestions from code review Co-authored-by: Matthew Treinish <mtreinish@kortar.org> --------- Co-authored-by: Matthew Treinish <mtreinish@kortar.org>
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Summary
The transpiler can transpile to a given target. In some situations there is no coupling map. This can occur at the beginning of device bring-up when the two-qubit gates have not yet been calibrated. In the absence of a coupling map the
FullAncillaAllocationfails to enlarge the circuit to a number of total qubits that match the number of qubits specified by the target. This PR fixes this behavior.Details and comments
The behavior is fixed by catching the case when coupling map is None. In this case we refer to the number of qubits specified by the target. The test illustrates the desired behavior.