Nice article, but not really a quantum computer or even a system that needs quantum mechanics to explain it. You could do the same calculation with an analog system (e.g. a capacitor that you add/remove charges to/from). The argument from Scott Aaronson about quantum advantage that the author refers to is really not very relevant, as a single qubit doesn't have any information encoding advantage over an analog system. A quantum computer simply cannot produce a speed advantage without relying on entanglement at some point during the quantum computation. So: no entanglement = no speed advantage.
Build a toy quantum computer at home
31–40 of 42 posts
Re: Build a toy quantum computer at home
#32It's more of a quantum demonstration than a computer, no?
It is not even a quantum demonstration.
Re: Build a toy quantum computer at home
#33Is it possible / are there virtual or emulated quantum computers?
I read about the Kyndi model but could not find any implementation.
Re: Build a toy quantum computer at home
#34I like it.
Re: Build a toy quantum computer at home
#35Earlier quoted context omitted.
Hey, you're right you could use a stick on a piece of paper etc. Totally fair. That being said this is in fact a real application where a qubit can model things a standard bit can't. Professor Aaronson describes it in this paper: https://www.scottaaronson.com/papers/qcoin13.pdf . Additionally, it's described in his lecture notes here: https://www.scottaaronson.com/qclec/5.pdf
Thanks for the links. It doesn't seem like your experiment captures the interesting part, which is that you don't need more qubits to measure a more subtle bias. As I understand the experiment now, it seems like the more subtle the bias in the coin, the more times you would need to rotate the polarizer to detect the bias. If there is something about using the polarizing filters to keep track of tries that is more eff…
Yup. As greek to me as the paper is at least it makes very clear what it sets out to achieve and why (and when) it differs. I suppose it's implicit but I feel article really ought to explain that in the demonstrated case of heavy bias, few attempts and fixed, coarse steps there is of course no advantage - apart from the stick in ground one could also best its resolution off 0b1000000 and ++/--.
It's a nice explainer on polarization but tries to be more than that and doesn't achieve it - but with further work (not in form of added caveats but rather a new approach to tying the two concepts together) I'm sure it could.
Re: Build a toy quantum computer at home
#36This is a real-valued computer, not a quantum computer. In the described algorithm the state is the real-valued angle of the polarizer. One could very well implement this algorithm using the charge on a capacitor. Also the algorithm has bugs, it can overshoot the vertical. The author does acknowledge these shortcomings in the "caveats" section. But with all those caveats, you are not building a quantum computer at ho…
The proper term would be "analog computer", but I agree with you. Really this is not even a computer.
Re: Build a toy quantum computer at home
#37This is a real-valued computer, not a quantum computer. In the described algorithm the state is the real-valued angle of the polarizer. One could very well implement this algorithm using the charge on a capacitor. Also the algorithm has bugs, it can overshoot the vertical. The author does acknowledge these shortcomings in the "caveats" section. But with all those caveats, you are not building a quantum computer at ho…
The proper term would be "analog computer", but I agree with you. Really this is not even a computer.
Indeed, I should have called it "analog computation" instead.
Re: Build a toy quantum computer at home
#38I liked the article, but this is not a quantum computer. Please do not take away the credibility of what a real quantum computer could achieve. This is at best an algorithm to reveal the angle of polarizer, and also the nature of light.
Although, appreciate the efforts.
Re: Build a toy quantum computer at home
#39While this is a nice demonstration of the polarization of light, this is not a demonstration of quantum mechanics, or quantum computing (though it does have pedagogical value, if qualified properly). Polarizers essentially just project the electric field of the wave onto some axis, zeroing out the perpendicular component. Keeping in mind that light intensity is the square of the electric field strength, all of this c…
> Polarizers essentially just project the electric field of the wave onto some axis
Where goes the energy of the orthogonal component of the field? Absorbed by the polarizer, reflected, ... ?
Re: Build a toy quantum computer at home
#40While this is a nice demonstration of the polarization of light, this is not a demonstration of quantum mechanics, or quantum computing (though it does have pedagogical value, if qualified properly). Polarizers essentially just project the electric field of the wave onto some axis, zeroing out the perpendicular component. Keeping in mind that light intensity is the square of the electric field strength, all of this c…
> Polarizers essentially just project the electric field of the wave onto some axis Where goes the energy of the orthogonal component of the field? Absorbed by the polarizer, reflected, ... ?
> Where goes the energy of the orthogonal component of the field? Absorbed by the polarizer, reflected, ... ?
It depends on the type of polariser.
The type used in LCD displays and 3D cinema glasses absorbs, that's why everything looks darker through them but they don't look like mirrors.
A polarising beam splitter reflects one mode and passes the other. It looks like a half-mirror.