Quantum Computers Offer a Faster Search for Bitcoin Mining Solutions
Summarize this article with:
Pierre-Luc Dallaire-Demers and colleagues at BTQ Technologies present the first end-to-end cost analysis of fault-tolerant hardware needed to use Grover’s algorithm for Bitcoin mining. The open-source estimator considers the entire attack surface, from reversible oracles to fleet logistics and energy consumption, revealing a key transition point where the required resources escalate sharply. The study shows that while a quantum advantage exists in theory, practical quantum mining quickly becomes unsustainable, demanding astronomical qubit counts and energy levels, potentially reaching Kardashev Type II civilisation scales, to achieve even minimal consensus effects. Quantum resource requirements preclude viable Bitcoin mining At January 2025 Bitcoin mining difficulty levels, a quantum miner would require approximately (10^{23}) qubits and consume around (10^{25}) watts of power. This energy demand is comparable to that of a Kardashev Type II civilization, effectively rendering practical quantum mining impossible with foreseeable technology. Prior to this analysis, assessments of quantum mining feasibility often relied on theoretical speedups or incomplete hardware costings, but a thorough end-to-end cost analysis now reveals the astronomical resources required for even minimal consensus effects. Scaling to match January 2025 Bitcoin mainnet difficulty, the qubit requirement surges to roughly (10^{23}) with power consumption reaching approximately (10^{25}) watts, nearing the energy demands of a Kardashev Type II civilization. The analysis incorporates detailed costing of reversible oracles for the SHA-256 mining process, surface-code factory sizing, and logistical considerations under Nakamoto consensus timing, all of which sharply inflate resource requirements beyond simple algorithmic speedups. Even under the most optimistic conditions, a quantum miner targeting a modest number of marked states, specifically (2^{224}), would still necessitate approximately (10^8) physical qubits and consume around (10^4) megawatts of power. This energy load is comparable to that of a large national grid. Recent work has estimated power per qubit, but this analysis uniquely prices the entire quantum stack, including oracle design and error correction overhead, revealing the true scale of the challenge. Reversible oracle construction and fault-tolerant cost modelling for Bitcoin mining This analysis hinged on developing an open-source estimator to carefully map the entire quantum attack surface for Bitcoin mining, a technique crucial for moving beyond theoretical speedups to realistic cost assessments. The estimator did not simply calculate qubit numbers; it thoroughly accounted for every component, beginning with the design of ‘reversible oracles’, specialised circuits mimicking the SHA-256 hashing algorithm used by Bitcoin, but capable of being run in reverse for quantum computation. These oracles were then linked to the demands of ‘fault-tolerant hardware’, computer components designed to correct errors during calculations, much like having multiple copies of a document to ensure accuracy even if some pages are damaged. To map the quantum attack surface for Bitcoin mining, an open-source estimator was developed, focusing on the practical costs of Grover’s algorithm which offers a quadratic speedup for searching. The estimator accounts for reversible oracles mimicking the SHA-256 hashing algorithm and the demands of fault-tolerant hardware, key for correcting errors during computation. A parametric sweep revealed that a superconducting surface-code fleet would require approximately 10 8 physical qubits and 10 4MW of power at a favourable setting. Economic limitations preclude Grover’s algorithm based Bitcoin mining at current qubit scales This analysis decisively demonstrates the impracticality of quantum mining with current technology, deliberately narrowing its scope to focus solely on hardware costs associated with Grover’s algorithm. The authors acknowledge this leaves open the question of potential mitigations within the Bitcoin protocol itself, such as alterations to the hashing algorithm or consensus mechanisms. Alternative proof-of-work systems, like those using quantum sampling of boson distributions or timed-random beacons, are also being explored, potentially sidestepping the vulnerabilities exposed here. Acknowledging ongoing work into quantum-resistant hashing algorithms and consensus mechanisms is important, as these explorations offer potential avenues for mitigating future threats. However, this detailed costing exercise firmly establishes that building a quantum computer capable of economically viable Bitcoin mining is currently beyond our reach. The scale of qubits, around 10^23 for even moderately challenging difficulty levels, and energy requirements approaching Kardashev Type II civilisation scales — equivalent to the output of a star — present insurmountable obstacles. The immense scale of quantum computing required to threaten Bitcoin mining was detailed by researchers, estimating fleets needing power comparable to a nation’s entire grid. While quantum attacks on Bitcoin signatures are already a concern, this analysis clarifies that economically viable quantum mining remains distant. This work establishes a clear physical threshold for quantum mining, moving beyond theoretical vulnerability to demonstrate practical impossibility with current and foreseeable technology. Determining that even optimistic scenarios require resources akin to a Kardashev Type II civilisation, one using the power of a star, resolves debate about whether quantum speedups translate to a genuine threat to Bitcoin’s proof-of-work system. Consequently, the focus shifts from if a quantum attack is possible to understanding the scale of resources needed to mount a successful one. Researchers determined that economically viable quantum mining of Bitcoin is currently impractical. Their analysis, factoring in the hardware needed for Grover’s algorithm and the energy demands of a fleet of approximately 10^23 qubits, revealed costs exceeding those of a large national power grid. This establishes a clear physical limit to quantum mining, suggesting the immediate threat lies with attacks on Bitcoin signatures rather than the mining process itself. Future work may concentrate on evaluating the feasibility of alternative proof-of-work systems or quantum-resistant cryptographic hashing algorithms to further bolster Bitcoin’s security. 👉 More information 🗞 Kardashev scale Quantum Computing for Bitcoin Mining 🧠 ArXiv: https://arxiv.org/abs/2603.25519 Tags: