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New Section

Soon I'm going to make a major upgrade to this article. You can see the expected version under User:Omrika/sandbox/QIP/Quantum_phase_estimation, still without references but with major changes and additions. Any comments? Omrika (talk) 16:50, 30 December 2016 (UTC)[reply]

I'm not a fan of this "C-U" notation. Older versions of the article didn't have it. I haven't seen it in any other quantum computing literature. I didn't know what C-U was until I figured out that it is not supposed to be "C minus U". I recommend reverting back to the old style as the controlled nature of the unitary is already given by the circuit diagram. The redundant information only adds confusion. — Preceding unsigned comment added by 202.66.60.168 (talk) 17:13, 27 January 2017 (UTC)[reply]

I agree that the "C" should go: the standard depiction of a controlled-U gate is the bullet connected to a box labeled "U" and the present notation is misleading. --Qcomp (talk) 16:17, 28 January 2017 (UTC)[reply]

Agreed.--Robin (talk) 21:02, 20 May 2018 (UTC)[reply]

Image

In the image of the circuit, it should be "QFT_{2^n}" not "QFT_n". — Preceding unsigned comment added by 2607:9880:1A17:FFE2:305B:9CC1:77FC:E0D2 (talk) 02:48, 12 March 2019 (UTC)[reply]

As long as the article is consistent, the current notation, QFT_n, is not wrong. From a cursory look at other sources it seems that the n dependence is often omitted altogether (for example it is on Nielsen and Chuang), so I don't see it as particularly troublesome to use QFT_n here (also, changing it would require recreating the image). — Preceding unsigned comment added by Luca Innocenti (talk • contribs) 11:33, 12 March 2019 (UTC)[reply]

|sin(x)| < |x|

Hello!

I may be missing something painfully obvious, but under the section Measurement we have

$|\sin(\pi \delta )|\leqslant |\pi \delta |{\text{ for }}|\delta |\leqslant {\frac {1}{2^{n+1}}}$

Doesn't $|\sin(x)|\leqslant |x|$ generally hold? Why the constraint on $\pi \delta$ ?

Miguelmurca (talk) 15:06, 13 March 2019 (UTC)[reply]

@@ Line 23: / Line 23: @@
 : As long as the article is consistent, the current notation, QFT_n, is not wrong. From a cursory look at other sources it seems that the ''n'' dependence is often omitted altogether (for example it is on Nielsen and Chuang), so I don't see it as particularly troublesome to use QFT_n here (also,  changing it would require recreating the image).  <!-- Template:Unsigned --><small class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Luca Innocenti|Luca Innocenti]] ([[User talk:Luca Innocenti#top|talk]] • [[Special:Contributions/Luca Innocenti|contribs]]) 11:33, 12 March 2019 (UTC)</small> <!--Autosigned by SineBot-->
+== |sin(x)| < |x| ==
+Hello!
+I may be missing something painfully obvious, but under the section [[Quantum phase estimation algorithm#Measurement|Measurement]] we have
+<math>| \sin(\pi \delta) | \leqslant | \pi \delta | \text{ for }  |\delta| \leqslant \frac{1}{2^{n+1}}</math>
+Doesn't <math> | \sin(x) | \leqslant |x| </math> generally hold? Why the constraint on <math> \pi \delta </math>?
+[[User:Miguelmurca|Miguelmurca]] ([[User talk:Miguelmurca|talk]]) 15:06, 13 March 2019 (UTC)