,
Supartha Podder
,
Dorian Rudolph
Creative Commons Attribution 4.0 International license
We study the power of quantum witnesses under perfect completeness. We construct a classical oracle relative to which a language lies in QMA₁ but not in QCMA when the QCMA verifier is only allowed polynomially many adaptive rounds and exponentially many parallel queries per round. Additionally, we derandomize the permutation-oracle separation of Fefferman and Kimmel, obtaining an in-place oracle separation between QMA₁ and QCMA. Furthermore, we focus on QCMA and QMA with an exponentially small gap, where we show a separation assuming the gap is fixed, but not when it may be arbitrarily small. Finally, we derive consequences for approximate ground-state preparation from sparse Hamiltonian oracle access, including a bounded adaptivity frustration-free variant.
@InProceedings{miloschewsky_et_al:LIPIcs.MFCS.2026.32,
author = {Miloschewsky, David and Podder, Supartha and Rudolph, Dorian},
title = {{En Route to a Standard QMA₁ vs. QCMA Oracle Separation}},
booktitle = {51st International Symposium on Mathematical Foundations of Computer Science (MFCS 2026)},
pages = {32:1--32:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-442-0},
ISSN = {1868-8969},
year = {2026},
volume = {386},
editor = {Kouck\'{y}, Michal and Petrișan, Daniela},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.MFCS.2026.32},
URN = {urn:nbn:de:0030-drops-274139},
doi = {10.4230/LIPIcs.MFCS.2026.32},
annote = {Keywords: Quantum complexity theory, Quantum Merlin-Arthur (QMA)}
}