TechDispatch #2/2020: Quantum Computing and Cryptography
Quantum computers can be highly beneficial to scientific developments due to the new, speedy way of performing computing. Once available, they however could break currently used cryptography and undermine the protection of (personal) data.
The physical laws of quantum mechanics allow for an alternative method to how today’s computers process information. Whereas traditional computers use bits (0 or 1) as a building block, quantum computers employ quantum bits, or qubits, that can be at the same moment a combination of |0⟩ and |1⟩.
The possible spectrum of values one qubit can adopt is best depicted by the surface of the Bloch sphere in Figure 1. While bits allow for two discrete values, qubits can store a point in a two-dimensional continuum, a surface of a sphere. Quantum computing can take advantage of those more powerful qubits and carry out operations not only for a determined value |0⟩ or |1⟩, but also for all possible superpositions at the same time. Consequently, quantum computing attains an efficiency advantage over binary computing for selected tasks. Some tasks would be rendered only feasible due to this efficiency boost, if the appropriate quantum computer hardware were available.
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