An Argument Against Quantum Computers
A note for the savvy: A quantum computer <i>is not</i> a magic bit-string that mysteriously flips to the correct answer. A n-qubit quantum computer <i>is not</i> like 2^n phantom computers running at the same time in some quantum superposition phantom-zone. That&#x27;s the popular misconception, but it&#x27;s effectively ignorant techno-woo.<p>Here&#x27;s what really happens. If you have a string of n-qubits, when you measure them, they might end up randomly in of of the 2^n possible configurations. However, if you apply some operations to your string of n-qubits using <i>quantum gates,</i> you can usefully bias their wave equations, such that the probabilities of certain configurations are much more likely to appear. (You can&#x27;t have too many of these operations, however, as that runs the risk of <i>decoherence</i>.) Hopefully, you can do this in such a way, that the biased configurations are the answer to a problem you want to solve.<p>So then, if you have a quantum computer in such a setup, you can run it a bunch of times, and if everything goes well after enough iterations, you will be able to notice a bias towards certain configurations of the string of bits. If you can do this often enough to get statistical significance, then you can be pretty confident you&#x27;ve found your answers.<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=IrbJYsep45E" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=IrbJYsep45E</a><p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=wUwZZaI5u0c" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=wUwZZaI5u0c</a><p>EDIT: I rather like Issac Arthur, but unfortunately, his Quantum Computing episode is an example of exactly this kind of popular misconception. I&#x27;ve called him out on it in comments.<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=wgCuKTN8sX0" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=wgCuKTN8sX0</a><p>EDIT: I can&#x27;t find my comment anymore, and I&#x27;ve also discovered that I&#x27;m now banned from the public Facebook group! Hmmm.<p>EDIT: It seems that Issac did correct his video, kind of. He still seems to advocate the 2^n parallelism, but then explains why that can&#x27;t work around 18 minutes in.