Qiskit / qiskit / 14907528220

88%

main: 88%

Build Type

push

github

Committed by web-flow

Commit Message

Fix incorrect error estimation in VF2 fallback (#14218) (#14316)

The VF2 passes include a fall-back error heuristic if the `Target`
specifies no error rates: a number proportional to the node degree is
used.  This was a proxy metric, used historically becasue IBM bowtie
devices (amongst others) were unreliable at reporting error rates but
had significantly degraded performance on higher-degree nodes.

The calculation of the node degree, however, could double count qubits
in a directional backend, and since the scaling factor is the total
number of qubits, this could cause error rates greater than one, which
then cause unpredictable behaviour on the scoring.

(cherry picked from commit 45778dd3c)

Co-authored-by: Jake Lishman <jake.lishman@ibm.com>

Run Details

2 of 2 new or added lines in 1 file covered. (100.0%)

25 existing lines in 2 files now uncovered.

72875 of 82730 relevant lines covered (88.09%)

356936.7 hits per line