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I saw a video in which a guy from IBM was explaining (very generally) quantum computing, it's difference with classical computing etc. The talk was not technical at all, it was intended for a broad audience.

At some point he told that, if we need to represent our position on the planet with only one bit, we could only tell for example if we are on the North or South hemisphere, but with a qubit we could tell exactly where we where.

He did this example to explain the difference in how much information can a bit and a qubit contain and to give a little idea of what a superposition is (I think).

Now, my question:

From what I know a qubit has more than one state, but when I read it I can only have one or zero, so why this example was made? From what I can understand a qubit can hold more information but I can't read it, so basically it's useless.

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    $\begingroup$ "From what I can understand a qubit can hold more information but I can't read it, so basically it's useless." Yes, you got that right. It's unfortunate that companies like IBM are promoting such vague (and highly misleading) notions. Oh well, they need to sell the hype to the general public. :) $\endgroup$ – Sanchayan Dutta Nov 28 '19 at 17:08
  • $\begingroup$ Before asking "How much information a qubit can hold" you must ask how information is measured; quantum information is measured in qubits; so the correct answer to the question is "a qubit holds one qubit of quantum information". $\endgroup$ – kludg Nov 29 '19 at 9:06
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    $\begingroup$ @kludg what you are saying is tautological and I'm not asking how much information a qubit can hold. $\endgroup$ – malloc Nov 29 '19 at 10:13