21–30 of 89 posts
Earlier quoted context omitted.
With one major difference. We know that fusion in some form is possible (for example, in the sun, or in a hydrogen-bomb). The difficulty is doing it at a reasonable scale. It's less clear that quantum computing is possible.
I mean we already have quantum computers too. https://quantumexperience.ng.bluemix.net/qx/experience The trouble here is also scaling, but in the upward direction.
I still need to gain the intuition for why a quantum computer can operate on some kinds of things "faster". I've read some of the math, but that did little to satisfy me (I need to study it more clearly). But all of this seems in a tragic state at the moment. Allowing rampant misinformation and hype as to what these machines are actually capable of.
I'm going to butcher a lot of the physics here, but here's the gist of it that should avoid some quantum myths: The quantum state of a system is not described by a simple real probability but by a complex number. This means that there is an additional degree of freedom that you can adjust in a quantum state that doesn't change its probability of occurring. The nature of entanglement means that there is constructive a…
This gave me a real 'aha' moment - I've been trying to get an intuition for complex numbers for years, thanks.
Earlier quoted context omitted.
I'm going to butcher a lot of the physics here, but here's the gist of it that should avoid some quantum myths: The quantum state of a system is not described by a simple real probability but by a complex number. This means that there is an additional degree of freedom that you can adjust in a quantum state that doesn't change its probability of occurring. The nature of entanglement means that there is constructive a…
OK, yes. This builds on the parts of my intuition that already exist. It's about building a system (from combinations of quantum operators) that maximizes the probability distribution of the result you want. I'm still unsure of the timeline of any quantum operator, and the "finding the interference" seems equivalent to saying something like "find the function" or something more classical.
Earlier quoted context omitted.
If you are specifically interested in building up the mathematical intuition, check out "Quantum Computing since Democritus" by Aaronson - it excels at presenting the intuition. For less comp-sci and more physics look at the standard references: Nielsen and Chuang's book and Preskill's lecture notes.
Thanks for the links. I'll start here: http://www.theory.caltech.edu/%7Epreskill/ph219/index.html#l... and probably get the books too (hey, they're cheap on amazon... god I hate myself).
Earlier quoted context omitted.
I'm going to butcher a lot of the physics here, but here's the gist of it that should avoid some quantum myths: The quantum state of a system is not described by a simple real probability but by a complex number. This means that there is an additional degree of freedom that you can adjust in a quantum state that doesn't change its probability of occurring. The nature of entanglement means that there is constructive a…
OK, yes. This builds on the parts of my intuition that already exist. It's about building a system (from combinations of quantum operators) that maximizes the probability distribution of the result you want. I'm still unsure of the timeline of any quantum operator, and the "finding the interference" seems equivalent to saying something like "find the function" or something more classical.
This is done applying the Quantum Fourier Tranform on each 'a^x mod N' using x+1 complex roots of unity for that value of x. You can visualise this as x+1 arrows from the centre of a unit circle with an angle 2pi/(x+1). So, for x=3 you have 4 arrows pointing up, down, left, and right.
When you stack the arrows end to end, they will loop back to their starting point (3 will form a triangle, 4 a square, etc.). The key is that when multiplting this quantum fourier transform with the value of 'a^x mod N', the 1s (at the period) will occur at the same point around the unit circle only for the cases where the number of complex roots is a multiple of the period.
This has the effect that for the correct answer, the arrows are lined up together in a single direction, amplifying the number and thus the probability of selecting that number. For the others, the arrows cycle and loop back on each other, so stay fairly small, decreasing the probability they will be selected.
I still need to gain the intuition for why a quantum computer can operate on some kinds of things "faster". I've read some of the math, but that did little to satisfy me (I need to study it more clearly). But all of this seems in a tragic state at the moment. Allowing rampant misinformation and hype as to what these machines are actually capable of.
Had to read to the bottom to get to the (really weak) "case against Quantum Computing": > I believe that, appearances to the contrary, the quantum computing fervor is nearing its end. That’s because a few decades is the maximum lifetime of any big bubble in technology or science. After a certain period, too many unfulfilled promises have been made, and anyone who has been following the topic starts to get annoyed by…
Sounds like Fusion. That’s still going on after 60 odd years.
Earlier quoted context omitted.
I mean we already have quantum computers too. https://quantumexperience.ng.bluemix.net/qx/experience The trouble here is also scaling, but in the upward direction.
The "quantum computers" we have are classical computers with very weird hardware. The thing everybody is trying to achieve is quantum supremacy - this hasn't been achieved or demonstrated yet, and might never will be.
Earlier quoted context omitted.
I mean we already have quantum computers too. https://quantumexperience.ng.bluemix.net/qx/experience The trouble here is also scaling, but in the upward direction.
The "quantum computers" we have are classical computers with very weird hardware. The thing everybody is trying to achieve is quantum supremacy - this hasn't been achieved or demonstrated yet, and might never will be.