Disadvantages and Security

The main disadvantage or problem in creating quantum computer lies in removing quantum decoherence (Wikipedia, 2011). Decoherence is a security issue when there are too many interacting qubits so that "quantum information will spread outside the quantum computer and be lost into the environment, thus spoiling the computation" (Quantiki, 2010). One of the ways to battle quantum decoherence is introduction of decoherence-free subspaces, which help to "prevent destructive environmental interactions by isolating quantum information" (Wikipedia, 2010). One of the things related to the security of the quantum computer is a field of quantum cryptography, which helps to "secure message transmission" and achieves a higher level of security than "purely classical schemes" (Quantiki, 2006). Although there are some disadvantages to quantum computers, the scientists work hard to remove them, which can lead to a better security of the information stored on these computers.