MattSparkes writes, "Today's quantum computers are not sophisticated enough to do anything malicious to your online bank account; the field is in its infancy. However, there are in theory more ways to attack quantum computers than classical ones. As quantum networking takes off, this is going to become a larger and more immediate problem." The Wikipedia article correctly identifies as an unsolved problem in physics the question of whether it is possible to construct a practical computer that performs calculations on qubits.
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