The increasing power of quantum computers creates a need for ways to reliably validate their results, particularly when computations occur on remote servers that may not be fully trusted. Bo Yang, alongside Elham Kashefi from LIP6, Sorbonne Université, and Harold Ollivier, addresses this challenge by developing a new protocol for verifying observable estimation, a crucial task for many near-term quantum applications. Their work overcomes limitations in existing verification methods, which struggle with problems where simple majority voting cannot guarantee a correct solution. This new protocol efficiently confirms that a quantum computer’s estimate of a value is accurate, or halts the process if it detects a significant error, requiring only a modest increase in computational complexity and maintaining a negligible error rate overall. This achievement represents a significant step towards building trustworthy quantum computing systems capable of delivering verifiable results.
Quantum Noise, Correction and Mitigation Strategies
This document presents a comprehensive overview of research related to quantum computing, verification, and error mitigation, exploring core themes and challenges in implementing quantum algorithms on current devices. A significant focus lies on quantum error correction and mitigation techniques, designed to improve the reliability of computations on noisy intermediate-scale quantum (NISQ) devices. The collection also details methods for verifying quantum computations, alongside topics like blind quantum computation for secure cloud computing, hybrid quantum-classical algorithms, and the challenges of barren plateaus in variational quantum algorithms. This resource serves as a valuable literature review for researchers, informing curriculum development, grant proposal writing, and professional development in this rapidly evolving field. By compiling the work of leading experts, the document offers a snapshot of the breadth and depth of current research.
Secure Observable Estimation with Interleaved Verification
Scientists have developed a novel protocol for verifiable blind observable estimation, addressing a critical need in secure delegated quantum computation. Recognizing limitations in existing verification techniques for tasks relying on expectation value estimation, common in quantum simulation and machine learning, the team pioneered a method to efficiently verify computations performed on untrusted quantum hardware. The work centers on constructing a Secure Delegated Observable Estimation (SDOE) resource, guaranteeing a computed estimate is within a tolerable error of the true expectation value or the computation aborts. To achieve this, researchers designed a protocol that randomly interleaves computation rounds with test rounds, mirroring recent Robust Verifiable Blind Quantum Computation (RVBQC) protocols, but minimizing computational cost by directly averaging outputs from computation rounds.
The team rigorously demonstrated that the SDOE resource can be constructed with negligible error, operating within the framework of abstract cryptography to ensure composable security. The methodology focuses on observable estimation problems, specifically computing the trace of a state multiplied by an observable, simplified by assuming the observable can be represented as a coarse-grained measurement. A key innovation lies in the direct averaging of outputs, bypassing complex quantum circuits typically required to estimate expectation values, enabling efficient verification of near-term quantum applications and preserving confidentiality.
Secure Remote Estimation With Verifiable Accuracy
The research team has developed a Delegated Observable Estimation (SDOE) protocol that allows for secure and verifiable computation on potentially untrusted remote servers, specifically for tasks where direct classical validation is impractical. This breakthrough guarantees a computed estimate remains within an acceptable margin of error or the computation is safely aborted, achieved by carefully balancing computation and test rounds. Experiments demonstrate that the SDOE protocol can construct a resource with negligible error, meaning the estimated value closely matches the true expectation value. The protocol’s security relies on a combination of blindness and verifiability, achieved through Unitary Blind Quantum Computation (UBQC).
The team proved that for a given ratio of computation to test rounds, the ability to distinguish the protocol from an ideal, perfectly secure resource becomes negligible as the number of rounds increases. The research establishes that the protocol’s distinguishing advantage diminishes rapidly with the number of computation rounds, and the probability of the estimator deviating beyond the acceptable error margin is minimal, confirming the protocol’s accuracy. The security proof leverages a simulator attached to the server’s interface, generating plausible transcripts and ensuring a distinguisher cannot differentiate between the protocol and the ideal resource, relying on the perfect blindness of UBQC.
Secure Delegation of Observable Estimation Achieved
This research introduces a new protocol for verifiable delegated computation, addressing the challenge of efficiently verifying observable estimation performed on potentially untrusted remote servers. The team developed a Delegated Observable Estimation (SDOE) protocol that guarantees a computed estimate is within a defined tolerance of the true value, or the computation halts, overcoming limitations in existing cryptographic protocols. The core of this work lies in the creation of a secure and verifiable resource, termed SDOE, and its implementation in the Verifiable Blind Observable Estimation (VBOE) protocol. This protocol operates through sequential rounds of testing and computation, tailored for observable estimation problems, and ensures a malicious server can only learn the class of problems the resource can handle and influence results within acceptable error bounds.
The team demonstrates that the overhead of this verification process is limited to adding test rounds comparable in complexity to the original computation, with negligible error. The authors acknowledge that the security of the VBOE protocol relies on assumptions about the computational class, representing the range of measurement patterns executable on a given graph. Future research directions include exploring the protocol’s performance with different graph structures and computational complexities, as well as investigating its resilience against more sophisticated adversarial strategies, and practical implementation on existing quantum computing platforms.
👉 More information
🗞 Verifiable blind observable estimation: A composably secure protocol for near-term quantum advantage tasks
🧠ArXiv: https://arxiv.org/abs/2510.08548