Reset Operations in Cloud Quantum Computers Enable Circuits to Run for Free
Summarize this article with:
The increasing accessibility of quantum computers through cloud-based services presents new challenges, not just in terms of technological hurdles, but also in economic security. Jakub Szefer from Northwestern University and colleagues demonstrate a novel method for exploiting reset operations within these cloud systems, effectively running multiple quantum circuits within a single charged ‘shot’.
This research reveals that current per-shot pricing models, while straightforward, are vulnerable to abuse through the strategic use of mid-circuit qubit measurement and reset, potentially leading to significant financial losses for companies offering cloud access. By carefully interleaving user circuits with reset operations, the team shows that it is possible to execute multiple computations for the price of one, reducing costs by a substantial percentage. This work highlights a critical vulnerability and proposes a clear path towards more robust and equitable charging mechanisms for quantum computing resources, while preserving the benefits of flexible mid-circuit operations. Many companies today offer access to their hardware through cloud-based services. Due to the inherent noise in quantum computers, a quantum circuit is run repeatedly to collect statistical data, with each run called a “shot”. Current pricing models typically charge users based on the number of these shots executed.
This research demonstrates that this per-shot pricing can be exploited to run circuits for free by abusing recently implemented mid-circuit qubit measurement and reset operations. Through evaluation on real quantum hardware and detailed simulations, the research reveals a fundamental flaw in current cloud service pricing models and highlights the need for more robust accounting mechanisms.
Qubit Reuse Exploits And Detection Methods This work details a novel attack on the economics of cloud-based quantum computing, demonstrating how to exploit reset operations to run circuits effectively for free. Researchers discovered that by strategically interleaving user circuits with reset operations, multiple computations can be executed within a single billed “shot”. This circumvents standard per-shot pricing models, where users are charged for each execution of a quantum circuit. Experiments on real, cloud-based quantum computers demonstrate the feasibility of this attack, showing that a malicious user can execute multiple circuits while only paying for one.
The team achieved this by leveraging mid-circuit qubit measurement and reset capabilities, recently implemented in many quantum computing platforms. By resetting all qubits to the |0⟩ state during execution, the system is prepared for a new computation within the same shot. Data from the qubits’ prior state is saved using mid-circuit measurement and stored in classical registers, allowing for recovery of results from each circuit. Free Circuits via Reset Operation Exploitation This work presents the first thorough investigation into how reset operations within cloud-based quantum computers can be exploited to run circuits without charge. Through evaluation on real quantum hardware, the researchers demonstrate that the cost of executing certain circuits can be reduced by nearly 900%, revealing a previously unrecognized vulnerability with significant financial implications for quantum computing providers. The findings highlight a fundamental issue where current per-shot billing models do not accurately reflect the underlying quantum operations being performed. To address this concern, the team proposes a revised billing approach based on per-gate execution, ensuring users are charged precisely for the quantum operations they utilize within each shot. This method preserves the usability of mid-circuit measurements and active reset operations while effectively mitigating the potential for abuse.
Reset Exploits Slash Quantum Circuit Costs Measurements confirm that the total per-shot cost to run certain circuits could be reduced by up to 900%, representing a significant potential financial loss for quantum computing companies. The research demonstrates a clear vulnerability in current pricing models, where the cost is determined by the number of shots executed. To address this, the team proposes an updated approach to charging users, maintaining the usability of mid-circuit measurement and reset operations while preventing this type of cost abuse. The researchers acknowledge that while antivirus programs could detect malicious circuits containing reset gates, attackers may find ways to circumvent these detection methods. Beyond the immediate solution, this work underscores the importance of aligning billing strategies with the physical operations of quantum computers to prevent unintended exploitation as the technology scales. The findings also demonstrate that features intended to improve efficiency, such as mid-circuit resets, can introduce new security vulnerabilities if not carefully managed. The vulnerability was responsibly disclosed to a quantum computer provider, who acknowledged receipt of the research but did not comment on the issue itself, and the team believes sufficient time has passed to publicly discuss their findings and proposed solution. 👉 More information 🗞 Exploiting Reset Operations in Cloud-based Quantum Computers to Run Quantum Circuits for Free 🧠 ArXiv: https://arxiv.org/abs/2512.14582 Tags: