Testwiki: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.

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Quantum computer

Review commentary

Messages left at Physics, Computing, Computer science and Technology. SandyGeorgia (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.

• There is a massive link farm labeled (incorrectly—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, ...

SandyGeorgia (Talk) 17:22, 8 April 2007 (UTC)

Factual problems

Complex numbers

Portions of the following are incorrect

In fact, the register is described by a wavefunction:

$|\psi ⟩=a|000⟩+b|001⟩+c|010⟩+d|011⟩+e|100⟩+f|101⟩+g|110⟩+h|111⟩$

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)

Number of states

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

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 −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 − 2. See Bloch sphere.

linas 23:18, 10 April 2007 (UTC)

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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, SandyGeorgia (Talk) 14:16, 11 April 2007 (UTC)

Bits vs. Qubits

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 Template:User 22:47, 16 April 2007

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. SandyGeorgia (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.