Real-time computers of the Noisy Intermediate Scale Quantum (NISQ) era undergo the undesirable coupling among qubits known as crosstalk. The negative effects of crosstalk errors can lead to degradation in the performance of various quantum circuits. In this paper, we present four crosstalk models that negatively affect the outcome of Grover’s search algorithm, Simon’s algorithm and the performance of the quantum teleportation protocol. The crosstalk models presented in this work are used as malicious circuits running alongside the victim circuits of the said quantum algorithms and protocol. This is possible in the shared cloud quantum computing environment which is right now offered by some of the industries. This work demonstrates the formation of some of the possible patterns as parts of the malicious circuits and their repetitions to inject crosstalk errors in the victim circuits. The analysis of the affected outputs for each pattern along with the corresponding diagrammatic representation is also done in this article along with the discussion on the degraded results for the used victim circuits other than the state-of-the-art works for the available ones. Moreover, this work highlights the need for proper counter-measures in order to detect and eliminate the malicious patterns that can harm the performance of a quantum circuit.
Real-time computers of the Noisy Intermediate Scale Quantum (NISQ) era undergo the undesirable coupling among qubits known as crosstalk. The negative effects of crosstalk errors can lead to degradation in the performance of various quantum circuits. In this paper, we present four crosstalk models that negatively affect the outcome of Grover’s search algorithm, Simon’s algorithm and the performance of the quantum teleportation protocol. The crosstalk models presented in this work are used as malicious circuits running alongside the victim circuits of the said quantum algorithms and protocol. This is possible in the shared cloud quantum computing environment which is right now offered by some of the industries. This work demonstrates the formation of some of the possible patterns as parts of the malicious circuits and their repetitions to inject crosstalk errors in the victim circuits. The analysis of the affected outputs for each pattern along with the corresponding diagrammatic representation is also done in this article along with the discussion on the degraded results for the used victim circuits other than the state-of-the-art works for the available ones. Moreover, this work highlights the need for proper counter-measures in order to detect and eliminate the malicious patterns that can harm the performance of a quantum circuit.
The noisy intermediate-scale quantum (NISQ) computers suffer from unwanted coupling across qubits referred to as crosstalk. Existing literature largely ignores the crosstalk effects which can introduce significant error in circuit optimization. In this work, we present a crosstalk modeling analysis framework for near-term quantum computers after extracting the error-rates experimentally. Our analysis reveals that crosstalk can be of the same order of gate error which is considered a dominant error in NISQ devices. We also propose adversarial fault injection using crosstalk in a multiprogramming environment where the victim and the adversary share the same quantum hardware. Our simulation and experimental results from IBM quantum computers demonstrated that the adversary can inject fault and launch a Denial-of-Service attack. Finally, we propose system- and device-level countermeasures.
Researchers are today exploring models for cloud-based usage of quantum computers where multi-tenancy can be used to share quantum computer hard-ware among multiple users. Multi-tenancy has a promise of allowing better utilization of the quantum computer hardware, but also opens up the quantum computer to new types of security attacks. As this and other recent research shows, it is possible to perform a fault injection attack using crosstalk on quantum computers when a victim and attacker circuits are instantiated as co-tenants on the same quantum computer. To ensure such attacks do not happen, this paper proposes that new techniques should be developed to help catch malicious circuits before they are loaded onto quantum computer hardware. Following ideas from classical computers, a compile-time technique can be designed to scan quantum computer programs for mali-cious or suspicious code patterns before they are compiled into quantum circuits that run on a quantum computer. This paper presents ongoing work which demonstrates how crosstalk can affect Grover's algorithm, and then presents suggestions of how quantum programs could be analyzed to catch circuits that generate large amounts of crosstalk with malicious intent.
Qubits, which are building blocks of quantum computers, are fragile and prone to noise and error. Some prominent errors include decoherence/dephasing, gate error, readout error, leakage, and crosstalk. The computation quality degrades in the presence of errors. Therefore, even though quantum computing can theoretically speed-up certain classes of problems, the present-day Noisy Intermediate-Scale Quantum (NISQ) computers can only solve small-scale ones. In this work, we present an overview of various noise sources and their impact on the resilience and the security of quantum circuits. Our analysis indicates that noise sources (e.g., crosstalk) create a new attack surface (e.g., fault injection), especially for future largescale quantum computers that may employ a multi-programming compute model. We also propose countermeasures against the reliability and security issues.
The rapid advancement of quantum computing has spurred widespread adoption, with cloud-based quantum devices gaining traction in academia and industry. This shift raises critical concerns about the privacy and security of computations on shared, multi-tenant quantum platforms accessed remotely. Recent studies have shown that crosstalk on shared quantum devices allows adversaries to interfere with victim circuits within a neighborhood. While insightful, these works left unresolved questions regarding the root cause of crosstalk, effective countermeasures, and replicability across circuits. We revisit the crosstalk effect, tracing its origins to the SWAP path between qubits and demonstrating its impact even over long distances. Our results significantly improve the understanding of this phenomenon beyond prior works. The proposed SWAP-based side-channel attack operates in both active and passive modes, as verified on real IBM quantum devices. In the active attack, an attacker executing a single CNOT gate can perturb victim circuits running Grover's Algorithm, reducing expected output accuracy by 81.62% through strategic qubit placement. Moreover, this effect can be modeled to identify qubits more susceptible to attack. The passive attack, leveraging a stealthy circuit as small as 6.25% of the victim's, achieves 100% accuracy in predicting the victim's circuit size when running Simon's Algorithm. These findings challenge the existing defense strategy of maximizing topological distance between circuits, showing that attackers can still extract sensitive information or manipulate results remotely. Our work highlights the urgent need for robust security measures to safeguard quantum computations against emerging threats.
Multi-tenancy schemes for quantum computing hardware are vulnerable to fault injection attacks through crosstalk effects. Research studies have experimentally demonstrated the change in output probabilities of victim circuits where the victim and the adversary share the same quantum hardware. To detect adversary circuits, this paper proposes compile time and simulation based protocols to scan quantum computer programs for malicious code patterns. In the compile time approach, with the help of databases of known malicious patterns, the number of gates and the repeating patterns in the code structures are tracked and validated for malicious intent. In the simulation based approach, Idle Tomography (IDT) using pyGSTi software framework is employed for crosstalk error rate extraction. Hamiltonian and Stochastic errors of relevant qubit pairs in accordance with the quantum hardware’s connectivity mapping are analyzed for the detection of unrecognized malicious adversary patterns. Both the protocols output metrics and error rates information that can be used as a "confidence ruler" over a concerned quantum hardware. These protocols safeguard honest quantum circuit parties from possible interference and resulting tampered computational outcomes brought about by adversary parties.
Hardware crosstalk in multi-tenant superconducting quantum computers poses a severe security threat, allowing adversaries to induce targeted errors across tenant boundaries by injecting carefully engineered pulses. We present a simulation-based study of active crosstalk attacks at the pulse level, analyzing how adversarial control of pulse timing, shape, amplitude, and coupling can disrupt a victim's computation. Our framework models the time-dependent dynamics of a three-qubit system in the rotating frame, capturing both always-on couplings and injected drive pulses. We examine two attack strategies: attacker-first (pulse before victim operation) and victim-first (pulse after), and systematically identify the pulse and coupling configurations that cause the largest logical errors. Protocol-level experiments on quantum coin flip and XOR classification circuits show that some protocols are highly vulnerable to these attacks, while others remain robust. Based on these findings, we discuss practical methods for detection and mitigation to improve security in quantum cloud platforms.