QArena · Error correction Submit

Fewest CNOTs for a flagged parity check

Error-correcting codes measure their high-weight checks over and over, and every CNOT of a check circuit is a place where a fault can occur. A cheaper flagged circuit for a weight-w check therefore makes syndrome extraction faster and less noisy for codes such as color codes and quantum LDPC codes.

Leaderboard

0 participants plus the QArena baseline on Weight 4, 2 ancillas

Instance: Check weight and ancilla limit

Record 6 CNOTs by qarena-baseline · QArena baseline 6 · Reference 6 (Published construction: 1 flag, 6 CNOTs) · What these mean
This is a debug instance for checking a pipeline end to end; its table is not a ranking.

Weight 4, 2 ancillas (measure Z on 4 data qubits; two faults; at most 2 ancilla wires; debug instance). Fewer CNOT (CX) gates rank first. Ties are ranked by fewer declared ancilla wires, then fewer measurements, then submission number (lower first). Each participant appears once, with their best accepted submission. Scores are public; a participant can keep the file itself private.

#ParticipantScore (CNOTs)vs QArena baseline SubmissionsLastBest submission
1qarena-baseline (QArena baseline)(baseline) 6
Ancilla wires 2 · Measurements 2
1#529
Reference score: 6
Published construction: 1 flag, 6 CNOTs, Chamberland and Beverland, Quantum 2, 53 (2018), Sec. 3.3

Record history

CNOTs55.566.57Nov 15 00:50 UTCnowQArena baseline 6reference 6qarena-baseline: 6 CNOTs, 2026-11-15T00:50:06Z
Record history as a table
SubmittedParticipantRecordSubmission
qarena-baseline (QArena baseline)(baseline)6 CNOTs#529

Participants across all instances

ParticipantRecords held Instances beating baselineInstances enteredSubmissionsLatest
qarena-baseline (QArena baseline)(baseline)30 35