Uncontrolled entropy? If you can repeatedly throw a ball and hit a target but not the bullseye, that doesn't mean you have no control, it just means you need to

Uncontrolled entropy? If you can repeatedly throw a ball and hit a target but not the bullseye, that doesn't mean you have no control, it just means you need to practice more. In the spirit of that, there are recent experimental demonstrations of logical qubits: - NV in diamond qubits (https://arxiv.org/abs/2108.01646 https://arxiv.org/abs/2108.01646) - Superconducting qubits (https://journals.aps.org/prxquantum/pdf/10.1103/PRXQuantum.2.010339 https://journals.aps.org/prxquantum/pdf/10.1103/PRXQuantum.2...) True, a universal logical gate set has yet to be practically realized (at least to my knowledge). But, it seems you're looking for perfection and QC will never be that – even with error correction. Fundamentally, QCs are analog and probabilistic; all discrete states we define theoretically will be approximations in practice if and when they can be demonstrated. But if the approximation is exponentially close to the target state and that is sufficient for the practical purpose at hand...does it matter?