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 i...
Sigh, have to fix these numbers: the 29 is a stupid typo, should have been 19, and this cascaded into the watt-hour calculation. Thanks to Pierre-Luc Dallaire-Demers for the correction. Will issue revised calculation momentarily.