>>11612767Because we don't have a quantum computer yet (where I use my definition of quantum computer := device which performs quantum error correction at its fault-tolerant threshold). In other words, the devices we have now are pitifully low on memory (qubit count) and useful circuit depth (coherence time). They can't do anything practical, not even fucking close.
That said, even if we DID have a fault-tolerant QC with thousands of *logical* qubits (which is millions of physical qubits under e.g. a surface code), how would you actually go about "calculating all the DNA sequences of COVID-19 and find the perfect cure"? Is this problem of "finding a perfect cure" quantifiable, and if so, how? What's the algorithm (classical or quantum), and does it even lie in BQP? If we have such an "efficient" algorithm, have people actually optimized it to be practical? Just because you require poly(n) space and time resources doesn't mean you actually have an implementable algorithm.
Basically, there's just a huge barrier to do what you're asking. A quantum computer isn't some sort of magical wizard who spouts out answers by you shouting questions at it (unless QMA = BQP, I suppose).
