https://arxiv.org/abs/2603.28846 estimates 2^29 qubits running 1/3 hour to break an ECC key. https://arxiv.org/abs/2304.14344 estimates 6 watts per qubit. 2^30 watt-hours costs about 0.1 million USD in electricity + cost of building hardware. More analysis can change numbers in either direction.
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