,
Thomas Vidick
Creative Commons Attribution 4.0 International license
The model of interactive oracle proofs (IOP) generalizes the notion of probabilistically checkable proof (PCP), in which a static proof is verified probabilistically by querying a small number of bits, to the interactive setting: a polynomial-time verifier interacts with an unbounded prover, but is restricted to only reading a small number of bits, in total, from the messages sent by the prover. IOPs provide a relaxed setting in which to study local probabilistic verification. They have proved instrumental in devising efficient methods for verification through subsequent compilation into non-interactive or succinct protoocls. We study a quantum analogue of interactive oracle proofs (qIOP) in which the verifier and communication are both allowed to be quantum; yet the verifier is restricted to perform measurements only on a small number of qubits received from the prover. Our main result is a qIOP for any language in QMA, in which the total communication is polynomial but the verifier only reads a polylogarithmic number of qubits in total. The protocol has completeness parameter exponentially close to 1 and soundness bounded away from 1 by a constant. In the absence of a quantum PCP theorem, this provides the first information-theoretically sound local and robust characterization of QMA, albeit interactive. Previous works in the information-theoretic setting either considered two isolated but entangled quantum provers or quantum verifiers whose effort in a single round is small but remains polynomial when aggregated across all rounds of the protocol. Our protocol combines the use of a quantum locally testable code (LTC) with classical techniques, notably probabilistically checkable proofs of proximity (PCPP). We avoid the necessity for complex multi-qubit tests employed in other settings by leveraging the local indistinguishability property of the quantum LTC.
@InProceedings{sun_et_al:LIPIcs.CCC.2026.4,
author = {Sun, Baocheng and Vidick, Thomas},
title = {{Probabilistically Checking Quantum Proofs, with Interaction}},
booktitle = {41st Computational Complexity Conference (CCC 2026)},
pages = {4:1--4:49},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-437-6},
ISSN = {1868-8969},
year = {2026},
volume = {383},
editor = {Moshkovitz, Dana},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CCC.2026.4},
URN = {urn:nbn:de:0030-drops-270463},
doi = {10.4230/LIPIcs.CCC.2026.4},
annote = {Keywords: quantum complexity theory, quantum probabilistically checkable proofs, interactive oracle proofs, quantum locally testable codes, QMA}
}