You are not logged in.
I've seen a number of articles indicating that despite substantial quantum computing hardware improvements, quantum computing software may not allow people to solve real world problems in a practical way due to fundamental mathematical limitations.
Here's the explanation:
Why I Left Quantum Computing Research
While it's true that a sufficient number of qubits can provide all possible outputs for a given set of inputs, all at the same time, what it cannot do is tell you what the actual answer to your math problem is. You can either record all outputs generated, nearly all of which are useless information that you will then discard by sequentially checking all outputs against the inputs to determine if they are true solutions, or you can receive a random output corresponding to the last computed value, which highly unlikely to be the answer.
This is merely another way of stating that the answer to a NP-complete problem may be near-instantly output using a sufficiently powerful quantum computer, but the limitation of the software, which is essentially a limitation of mathematics, means it's lost in a sea of useless data because software doesn't exist to allow you to identify which outputs are correct answers without sequential output validation.
Q: What's the point of using a quantum computer to "solve" a NP-hard or NP-complete problem?
A: There isn't any, because the very nature of the mathematics involved doesn't allow it.
The very definition of a NP-complete problem accurately describes why a solution is so computationally expensive. Even if your hardware allows you to instantly derive all possible outputs, your software still can't identify the solutions. There are a highly constrained set of computationally-intensive classical mathematics / computer science problems quantum computers can be usefully applied to. Combinatorics, prime number based encryption, and computational chemistry don't seem to be included amongst the problems these computers can provide rapid answers to.
A number of leading chemistry researchers who had previously hoped to use quantum computers to perform computational chemistry have authored a paper indicating that they think no further funding from computational chemistry budgets should be allocated to quantum computing development until software can be devised or critical inputs empirically predetermined, which means "doing the chemistry in real life". Performing the chemistry in a lab defeats the purpose of computational chemistry, which sought to avoid having to do time consuming real world work to tell chemists how new chemical compounds might be synthesized and how much energy input would be required.
There may eventually be staggering usable computational power derived from quantum computers, which is reason enough to continue quantum computer hardware development, but a "real breakthrough" will only materialize through as-yet unrealized mathematical advances.
Maybe I'm the only one, but I find it mildly amusing that the very nature of the questions being asked precludes our ability to derive any "fast and easy" answers. Is there a lesson in there somewhere? I certainly hope so.
Offline
Like button can go here