
Briefing
The core research problem addresses the long-standing ambiguity surrounding the necessary conditions for quantum advantage, where prior work predominantly established only sufficient criteria. This paper introduces a foundational breakthrough by presenting a novel framework that unifies the concepts of quantum advantage and cryptographic security. The single most important implication is the revelation that the non-existence of quantum advantage fundamentally compromises the security of nearly all established cryptographic primitives, extending beyond quantum-specific schemes to widely-used conventional and post-quantum cryptography, thereby providing a robust theoretical bedrock for future quantum technology development.

Context
Before this research, the precise conditions under which quantum computers could definitively outperform classical machines, known as quantum advantage, remained largely undefined. While various sufficient conditions for achieving quantum advantage had been proposed, a clear understanding of the necessary conditions was absent. This theoretical limitation presented a significant academic challenge, as it left the fundamental boundaries and prerequisites for quantum supremacy incompletely characterized.

Analysis
The paper’s core mechanism centers on establishing a profound equivalence between quantum advantage and the security of a specific cryptographic primitive ∞ the one-way puzzle. The researchers achieved this by focusing on “inefficient-verifier proofs of quantumness” (IV-PoQ), which are interactive protocols allowing a classical verifier to confirm a quantum prover’s computational power without possessing a quantum computer. The breakthrough demonstrates that the existence of these IV-PoQ protocols is directly dependent on the security of one-way puzzles. This model fundamentally differs from previous approaches by shifting the characterization of quantum advantage from purely computational metrics to a cryptographic foundation, revealing that if one-way puzzles are insecure, quantum advantage cannot exist, and vice-versa.

Parameters
- Core Concept ∞ Cryptographic Characterization of Quantum Advantage
- New Primitive ∞ One-Way Puzzle
- Key Protocol ∞ Inefficient-Verifier Proofs of Quantumness (IV-PoQ)
- Key Authors ∞ Tomoyuki Morimae, Yuki Shirakawa, Takashi Yamakawa
- Publication Venue ∞ Proceedings of the 57th Annual ACM Symposium on Theory of Computing

Outlook
This research opens significant new avenues for theoretical investigation, particularly in extending the cryptographic characterization to other forms of quantum advantage, fostering a more generalized theoretical framework. The established equivalence provides a stronger, more rigorous cryptographic foundation for future experimental demonstrations of quantum advantage. In the next three to five years, this theory could unlock deeper insights into the fundamental limits of computation, guiding the development of quantum-safe cryptographic systems and refining the strategic roadmap for quantum computing applications by clarifying its inherent capabilities and limitations.

Verdict
This research delivers a decisive judgment on quantum advantage, establishing its existence as intrinsically tied to the security of foundational cryptographic primitives, thereby solidifying the theoretical underpinnings of both fields.
Signal Acquired from ∞ kyoto-u.ac.jp