Why the fuss? Because many, not entirely incomprehensibly, were daunted by two major and seemingly insurmountable obstacles. First of all: quantum computers operate in the exponentially large Hilbert space, consisting of an equally exponential number of energy levels. Surely, sceptics argued, such a machine would require an exponentially precise control system, composed of utterly utopic lasers. And then came the other problem: decoherence. This merciless phenomenon reduces entangled quantum states to classical states due to interaction with the environment.
