Quantum computer

Comment:

What makes a quantum computer impractical?

Follow-up:

For now, the greatest difficulty is in the implementation of a quantum circuit that is stable. In fact, the problems related to accurately and reliably measuring the quantum bits, namely de-coherence and error correction, are still very difficult to solve in practice, even if we assume we can deploy tremendous amount of resources at the construction of a quantum computer.

Still remember the chaotic theory? It is also anticipated that if we cannot tackle the accurate measurement problem effectively, it would be impossible to scale up the size of a quantum circuit without leading to enormous errors.