arXiv subjects

Yizhuo Tan

Publications and source records attributed to Yizhuo Tan.

5 recordsLinked to original sources

arXiv2026

OQRAM: Oblivious Quantum Random Access Memory for Securing Delegated Quantum Queries

Quantum query is a basic subroutine in many quantum algorithms, and Quantum Random Access Memory (QRAM) provides a natural way to realize such coherent query access. In delegated settings, however, a standard QRAM query interface can expose sensitive information to the server. This paper introduces oblivious QRAM, a cryptographic abstraction for privacy-preserving delegated coherent query access. The protocol consists of an offline refresh phase and an online protected query phase. The database is stored in an encrypted and shuffled layout, and each query is protected by coherent address masking using either a quantum-secure pseudorandom permutation (qPRP) based method or a quantum one-time pad (qOTP) based method. In the adopted client model, the online protection adds only modest quantum overhead beyond the query register, avoiding the exponential quantum resources that would otherwise be required by an equivalent local QRAM construction. The qPRP-based variant also supports multi-query use by distributing database refresh across multiple queries to reduce classical communication. To address malicious servers, decoy checks are further incorporated to strengthen privacy protection and enable probabilistic tampering detection. Compared with fully blind quantum computing, this framework provides a lighter abstraction tailored to private delegated QRAM access, significantly reducing quantum resource requirements on both the client and server sides and achieving an exponential reduction in quantum communication.

quant-ph↗

arXiv2026

EPAR: Electromagnetic Pathways to Architectural Reliability in Quantum Processors

As superconducting processors scale, understanding how physical layout shapes qubit interactions is essential for architectural reliability. Existing methods offer limited insight into how electromagnetic design choices translate into execution-level behavior. We present EPAR, an electromagnetic-to-architecture framework that predicts robustness early directly from physical design by reconstructing how design distortion modifies the effective Hamiltonian, reroutes mediated connectivity, and influences control-pulse response. Across all tested layouts, EPAR's structural scores show 100% agreement with two-qubit error trends yet reveal over 10X robustness differences among edges with identical calibrated error rates, going beyond conventional metrics to provide improved and actionable compiler guidance.

cs.ET↗

arXiv2025

QubitHammer: Remotely Inducing Qubit State Change on Superconducting Quantum Computers

To address the rapidly growing demand for cloud-based quantum computing, various researchers are proposing shifting from the existing single-tenant model to a multi-tenant model that expands resource utilization and improves accessibility. However, while multi-tenancy enables multiple users to access the same quantum computer, it introduces potential for security and reliability vulnerabilities. It therefore becomes important to investigate these vulnerabilities, especially considering realistic attackers who operate without elevated privileges relative to ordinary users. To address this research need, this paper presents and evaluates QubitHammer, the first attack to demonstrate that an adversary can remotely induce unauthorized changes to a victim's quantum circuit's qubit's state within a multi-tenant model by using custom qubit control pulses that are generated within constraints of the public interfaces and without elevated privileges. Through extensive evaluation on real-world superconducting devices from IBM and Rigetti, this work demonstrates that QubitHammer allows an adversary to significantly change the output distribution of a victim quantum circuit. In the experimentation, variational distance is used to evaluate the magnitude of the changes, and variational distance as high as 0.938 is observed. Cross-platform analysis of QubitHammer on a number of quantum computing devices exposes a fundamental susceptibility in superconducting hardware. Further, QubitHammer was also found to evade all currently proposed defenses aimed at ensuring reliable execution in multi-tenant superconducting quantum systems.

quant-ph↗

arXiv2025

Evaluation of Noise and Crosstalk in Neutral Atom Quantum Computers

This work explores and evaluates noise and crosstalk in neutral atom quantum computers. Neutral atom quantum computers are a promising platform for analog Hamiltonian simulations, which rely on a sequence of time-dependent Hamiltonians to model the dynamics of a larger system and are particularly useful for problems in optimization, physics, and molecular dynamics. However, the viability of running multiple simulations in a co-located or multi-tenant environment is limited by noise and crosstalk. This work conducts an analysis of how noise faced by simulations changes over time, and investigates the effects of spatial co-location on simulation fidelity. Findings of this work demonstrate that the close proximity of concurrent simulations can increase crosstalk between them. To mitigate this issue, a Moving Target Defense (MTD) strategy is proposed and evaluated. The results confirm that the MTD is a viable technique for enabling safe and reliable co-location of simulations on neutral atom quantum hardware.

quant-ph↗

arXiv2025

Securing HHL Quantum Algorithm against Quantum Computer Attacks

As the quantum research community expands and new quantum algorithms are created and implemented, it is essential to consider the security implications and potential threats that could lead to the compromise the information processed by them. This work focuses on securing the HHL quantum algorithm against attacks while it executes on a quantum computer. Specifically, two types of potential attacks could be deployed on a cloud-based quantum computer by an attacker circuit attempting to interfere with the victim HHL circuit: the Improper Initialization Attack (IIA) and the Higher Energy Attack (HEA). To protect the HHL algorithm from IIA and HEA, this work proposes first-of-a-kind defense strategies against these attacks on the HHL quantum algorithm. Next, this work demonstrates an implementation of a new quantum circuit for the HHL quantum algorithm that incorporates these defenses. The redesigned quantum circuit is necessary to successfully apply and realize all proposed defense strategies. Finally, this work illustrates how these defense strategies function in practice in the redesigned circuit, specifically how they can protect the HHL quantum algorithm from both IIA and HEA across multiple qubits involving all three types of qubits used in the HHL algorithms: ancilla, clock, and b. The defense requires minimal modification to the circuit, and has only a very small effect on the fidelity of the circuits. The circuits have been tested and validated in both simulation, and also on real IBM quantum computer hardware. The work further analyzes how the modified HHL circuit with the defenses is affected by noise during quantum computation. This work in the end demonstrates that it is practical to add protections to quantum circuits so that they not only perform correct computation, but also self-detect if an attack has occured during the execution.

cs.CR↗