Breakthrough Tracker record

Separating QMA from QCMA with a classical oracle

The authors constructed a classical-oracle setting in which QMA, the class with quantum witnesses, is strictly larger than QCMA, whose witnesses are classical. The proof uses a decision problem called spectral Forrelation.

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Stable ID
qma-qcma-classical-oracle-2026
Revision
qma-qcma-classical-oracle-2026.v1
Field
Computer Science · Quantum complexity theory
Evidence
Tier 1 · Peer reviewed: Yes
Record state
Current · Verified/published conference result
Last checked

AI role

No AI assistance was disclosed in the paper or linked reporting.

Record details

Problem or result
Whether quantum proofs can be strictly more powerful than classical proofs checked by a quantum verifier
Authors
John Bostanci, Jonas Haferkamp, Chinmay Nirkhe and Mark Zhandry
Institutions
Columbia, Saarland/Harvard, University of Washington, Stanford and NTT Research
Result date
November 12, 2025; published at STOC 2026 on June 9, 2026

Why it matters

It supplies the oracle separation quantum-complexity researchers had sought for roughly two decades and introduces techniques that may be useful beyond this problem.

Limits

This is a relativized oracle separation, not an unconditional proof that QMA differs from QCMA in the ordinary unrelativized setting. It is not a demonstrated hardware advantage.

Sources

  1. Primary: Final ACM STOC 2026 proceedings record
  2. Primary: Primary paper on arXiv
  3. Primary: Author publication record confirming STOC 2026 Best Paper
  4. Independent: Quanta Magazine explanation
  5. Independent: Ruhr University report on the STOC Best Paper Award

Correction and revision history

  1. July 22, 2026 — Added the final ACM STOC 2026 proceedings record and changed “accepted” to “published.” The theorem statement and verification status are unchanged.

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