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 all aspects of a quantum attack, from reversible oracles to energy consumption at a scale comparable to national power grids. The study reveals that while a modest quantum advantage might be achievable under certain conditions, scaling to Bitcoin’s current security levels demands astronomical qubit counts, potentially reaching 10^23, and energy consumption approaching the Kardashev Type II civilisation threshold. This effectively demonstrates the impracticality of quantum mining with foreseeable technology.\n\n
Quantum resource thresholds preclude near-term Bitcoin mining viability
\n\nQubit requirements to mine Bitcoin at January 2025 difficulty levels would reach approximately 10²³. This figure exceeds the number of atoms in a large building and represents a previously uncosted threshold for quantum mining feasibility. Such immense scale dwarfs earlier estimations reliant on theoretical speedups, revealing the practical limitations of using Grover’s algorithm for Bitcoin mining due to the sheer volume of fault-tolerant hardware needed. Achieving even a modest quantum advantage necessitates energy consumption approaching 10²⁵ watts, approaching the Kardashev Type II threshold — comparable to the total energy output of a star — effectively placing quantum mining beyond the scope of foreseeable technology.\n\nA superconducting surface-code fleet attempting to mine Bitcoin at January 2025 difficulty levels would require approximately 10 8 physical qubits and consume around 10 4 megawatts of power. At the projected January 2025 mainnet level, the qubit requirement surges to roughly 10 23, with energy consumption reaching approximately 10 25 watts, nearing a Kardashev Type II civilisation scale. This substantial demand escalates dramatically with increasing difficulty. Such a power draw is comparable to the entire output of a large nation, highlighting the immense scale of resources needed. The analysis also considered the energy cost of reversible oracles for the double-SHA-256 mining process, alongside the logistical demands of operating a vast quantum computer fleet; even optimistic estimates of power efficiency per qubit do not alter the overall conclusion.\n\n
Grover’s Algorithm Hardware Requirements and Surface-Code Error Correction for Bitcoin Mining
\n\nThe analysis hinged on a detailed, open-source estimator designed to map the theoretical speedup of Grover’s algorithm into concrete hardware requirements. Grover’s algorithm is a faster, but still computationally intensive, way to search a database, akin to using a more efficient librarian to find a specific book. This estimator carefully accounted for every component of a potential quantum attack, beginning with the creation of ‘reversible oracles’, specialised quantum circuits needed to perform the cryptographic hashing at the heart of Bitcoin mining. The team then modelled ‘surface-code’ error correction, a grid of qubits that act like a team of proofreaders, each checking its neighbours for errors to ensure accurate calculations, a vital step for building a stable quantum computer.\n\n
Bitcoin’s quantum vulnerability assessment excludes protocol adaptation costs
\n\nThis analysis decisively demonstrates the impracticality of quantum mining with foreseeable technology, deliberately narrowing its scope to hardware costs. The authors acknowledge that their analysis doesn’t address potential defensive measures within the Bitcoin protocol itself, such as changes to signature schemes or hashing algorithms designed to increase quantum resistance. This omission highlights a critical tension; focusing solely on the attacker’s resources neglects the possibility of Bitcoin adapting to mitigate the quantum threat, a changing interaction not fully captured by static cost assessments.\n\nAcknowledging the potential for Bitcoin to evolve defensive mechanisms is important, yet this analysis delivers a strong baseline understanding of the sheer scale of resources required for a quantum attack on its mining process. It firmly establishes that even with optimistic assumptions about hardware development, a successful attack necessitates a quantum computer exceeding the capacity of any existing or realistically foreseeable infrastructure. The analysis definitively establishes that using quantum computation to mine Bitcoin is not practically viable with current or foreseeable technology. By carefully detailing the hardware and energy demands, it moves beyond theoretical speedups to quantify the immense scale required for a quantum attack on the Bitcoin network. It clarifies that the primary quantum threat to Bitcoin remains attacks on the cryptographic signatures, rather than the ability to generate new blocks through mining.\n\nThe research demonstrated that quantum mining of Bitcoin is practically impossible with current or near-future technology. Calculations revealed a quantum computer capable of mining at even a moderate level would require approximately 10 8 physical qubits and 10 4 megawatts of power, scaling rapidly to 10 23 qubits and 10 25 watts at current Bitcoin network difficulty. This analysis focused solely on the hardware costs of a quantum attack, acknowledging that Bitcoin could potentially adapt its protocols to increase quantum resistance. Consequently, the primary quantum vulnerability remains attacks on the cryptographic signatures used to secure transactions, rather than the mining process itself.\n\n
