Wikipedia:Featured article review/Quantum computer/archive1


 * The following is an archived discussion of a featured article review. Please do not modify it. Further comments should be made on the article's talk page or at Wikipedia talk:Featured article review). No further edits should be made to this page.

The article was removed 08:25, 13 May 2007.

Review commentary

 * Messages left at Physics, Computing, Computer science and Technology. Sandy Georgia (Talk) 17:22, 8 April 2007 (UTC)

Quantum computer is a "brilliant prose" promotion (no original author) that had a scanty review in May 2006. Sandy Georgia (Talk) 17:22, 8 April 2007 (UTC)
 * There is a massive link farm labeled (incorrectly&mdash;WP:GTL) as "Further reading".
 * Citations are not formatted and the article needs a review for citations.
 * There are red links in See also; also, See also should be minimized per WP:GTL, incorporating articles into the text and deleting from See also those that are already included in the text.
 * Strange bolding throughout and incorrect use of dashes, indicating the need for a copyedit.
 * External jumps (example: D-Wave Systems Inc. (dwavesys.com) ... )
 * Poor prose when incorporating other articles, example:  See Bloch sphere.
 * Mathematical formulas wrap off screen.
 * Incorrect italicization and/or use of See also or Seealso template: For discussion of foundational aspects of quantum computing, see the article on quantum circuits.
 * WP:MSH issues; title repeated often in TOC.
 * Weasly, example: It is widely believed that if large-scale quantum computers can be built, ...

Factual problems
Portions of the following are incorrect
 * Complex numbers


 * In fact, the register is described by a wavefunction:
 * $$|\psi \rangle = a\,|000\rangle + b\,|001\rangle + c\,|010\rangle + d\,|011\rangle + e\,|100\rangle + f\,|101\rangle + g\,|110\rangle + h\,|111\rangle$$

Yes, that's OK.
 * If a>b>c>d>e>f>g>h, then a+h=b+g=c+f=d+e.

Huh? these are complex numbers, these can't be simply ordered. This is just wrong.


 * For example:
 * (2.166/4.4)|000>+(1.966/4.4)|001>+(1.766/4.4)|010>+(1.566/4.4)|011>+(1.434/4.4)|100>+(1.234/4.4)|101>+(1.034/4.4)|110>+(0.834/4.4)|111>
 * (2.166/4.4)2+(1.966/4.4)2+(1.766/4.4)2+(1.566/4.4)2+(1.434/4.4)2+(1.234/4.4)2+(1.034/4.4)2+(0.834/4.4)2 = 1

WTF. Just delete this.


 * where the coefficients a, b, c,... are complex numbers...

this is correct. I'll make edits to cut out the questionable stuff shortly. linas 23:13, 10 April 2007 (UTC)

I turned the following remark into a footnote, as it is trite and irrelevant:
 * Number of states


 * Note that the coefficients are not all independent, since the probabilities must sum to 1. The representation is also (for most practical cases) non-unique, since there is no way to physically distinguish between a particular quantum register and a similar one where all of the amplitudes have been multiplied by the same phase such as &minus;1, i, or in general any number on the complex unit circle. One can show the dimension of the set of states of an n qubit register is 2n+1 &minus; 2. See Bloch sphere.

linas 23:18, 10 April 2007 (UTC)

Other than the two problems above, which I've corrected, the article appears to be scientifically correct, from the point of view of quantum mechanics. linas 23:55, 10 April 2007 (UTC)


 * I've corrected the formatting on section headings as they were distorting the entire TOC at WP:FAR. Please take care with excessive TOC headings at FAR.  Thanks, Sandy Georgia  (Talk) 14:16, 11 April 2007 (UTC)

This section gives a short description of qubits, but in my view does not sufficiently contrast them to bits, as the section title would indicate. One may note e.g. that 2^n is also the number of bit sequences that n bits can represent. The indicated number of states for qubits should be directrly compared against bits to make this section more clear and true to its purpose. Added by 22:47, 16 April 2007
 * Bits vs. Qubits

FARC commentary

 * Suggested FA criteria concerns citation sufficiency and formatting (1c), links, jumps, and other formatting issues (2), and prose (1a). Marskell 10:31, 25 April 2007 (UTC)


 * Remove per 1c. "Further reading" is also an external link farm in disguise. LuciferMorgan 11:30, 29 April 2007 (UTC)
 * Comment I've been cutting the link farm down to size and adding appropriate footnotes, but it's probably not satisfactory yet. Anville 15:36, 7 May 2007 (UTC)


 * Remove, issues raised on FAR almost entirely unaddressed. Sandy Georgia  (Talk) 12:49, 9 May 2007 (UTC)


 * Remove per the above. Trebor 14:38, 12 May 2007 (UTC)
 * The above discussion is preserved as an archive. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article review. No further edits should be made to this page.