Qubits are the basic unit of quantum information and are able to hold far more information than classical bits. This metric quantifies the number of qubits implemented in solid state superconducting quantum computers. We expect that the number of available qubits will grow exponentially in time in the near future. The optimistic assumption is that the number will double every 10 months whereas the less optimistic assumption assumes the number doubles every 20 months. The data points are taken from the following table

Read moreGate infidelity is used to measure how noisy a quantum gate is. We assume that the gate infidelity will continue to drop exponentially but that this development will stall at an infidelity of 5 · 10^{−7} (optimistic case) or 5 · 10^{−6} (less optimistic case). For the optimistic case we expect that the gate infidelity will continue to follow DeVincenzo’s law which predicts a reduction of the infidelity by a factor of 2 per year. The data points are taken from the following table

This plot shows two estimates of the time (in seconds) required for a quantum computer to break the Elliptic curve signature scheme (blue curves) as a function of time for the next 25 years. We give more and less optimistic estimates (red striped lines). Signatures in Bitcoin are made using the Elliptic Curve Digital Signature Algorithm (ECDSA) and are based on the secp256k1 curve and the discrete logarithm problem. While ECDSA digital signature is classically safe, a quantum computer with 485550 qubits can crack it within 600 seconds (red dotted horizontal line), rendering the current Bitcoin system highly insecure, as early as 2027.

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