[bugfix] Probabilities do not sum to one with Torch #5462
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Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #5462 +/- ##
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- Coverage 99.68% 99.67% -0.01%
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Files 402 402
Lines 37540 37287 -253
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- Hits 37420 37166 -254
- Misses 120 121 +1 ☔ View full report in Codecov by Sentry. |
mudit2812
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albi3ro
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albi3ro
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Context: When computing the
expvalof an operator using a quantum device with thetorchinterface anddefault_dtypeset totorch.float32, the probabilities do not sum to one. This error does not occur ifdefault_dtypeis set totorch.float64.Description of the Change: A renormalization of probabilities is introduced to overcome the issue. Such renormalization of probabilities occurs whenever the following two conditions are satisfied: 1) There is at least one probability that does not sum precisely to one, and 2) Such difference for all probabilities is between
0and1e-07.Benefits: The error is not raised anymore.
Possible Drawbacks: The main drawback is that renormalization can occur in cases where it should not happen, although it is unlikely since the cutoff
1e-07is expected to be reasonably small to prevent such cases (but large enough not to raise the error anymore).Related GitHub Issues: #5444
[sc-59957]