Superposition and entanglement get thrown around loosely, and when people ask me which one causes the most trouble, the honest answer is that the biggest problem is not really a misunderstanding of either. It is more of an ambiguity. People say that a quantum computer tests all solutions simultaneously and then selects the right one, and that is not literally correct. But it is also not the clean error it looks like.
The confusion almost certainly traces back to the most famous quantum computing algorithm there is, which is Shor's algorithm, discovered by Peter Shor in the early nineties. Shor's algorithm is the one that would allow us to decrypt RSA and other asymmetric key based encryption methods. It achieves a shortcut to factoring a very large number down to its primes, and that factoring problem is the basis for most modern encryption.
The way it does that is through quantum phase estimation. You have a very large computational space created by a set of qubits that are entangled with one another, referred to as a Hilbert space, which is essentially two to the power of the number of qubits you have as the theoretical limit of your computational space. What the algorithm does inside that space is purposely create interference patterns. The wave functions of the equation interfere with one another so that the correct answer gets amplified and the incorrect answers get suppressed. And that is similar enough to trying all the solutions at once that you can see why the shorthand took hold.
I actually interviewed Peter a couple of times, and the last time I talked to him I asked how he felt about it. When he hears somebody make that mistake of saying the algorithm tries all the solutions at once and then selects the right one, does it bother him. He thought about it for a moment and said, well, I mean, it's not really wrong.
That answer captures something true about this whole field. With all things quantum there is no real black and white, and the reason has been intriguing to me from the very beginning. All of this behavior, all of these attributes, exist so far from our lived experience. It is not the physical world. We cannot project physical and human metaphor into the quantum scale without making these very inaccurate generalizations, and every metaphor we reach for introduces some distortion in exchange for making the idea graspable. One of the things I find genuinely fascinating about working in this area is the communication challenge of grappling with ideas this ambiguous and this foreign.
So the practical version for anyone assessing quantum claims is to stop treating the parallelism explanation as the thing to correct people on, and start asking where the advantage actually comes from in a specific case. When someone describes a quantum speedup, ask which algorithm produces it and whether the mechanism is interference structure rather than brute parallel search, because that distinction tells you whether the problem genuinely fits. And when you explain any of this to your own team, name the limit of whichever metaphor you use in the same breath you use it, so nobody walks away carrying a picture that will mislead them later.