Talk:Partial trace

This article needs a revamp. Many things are undefined. Sloppy.

OK what things are sloppy? Note that

• It is correctly defined.
• It is stated how to compute it matricially
• Its relation to averaging out is clearly stated.

Could you be more specific as to what's missing? Where terms are undefined in the article, links are given to where you can find the definition. WIkipedia policy suggests being bold, but that refers to actually doing something constructive. Sitting on the sidelines passing judgment doesn't fall into that category.--CSTAR 23:08, 10 April 2006 (UTC)

I am not the author of the above complaint, but right off the bat I notice that T and L(...) are undefined, so I kind if hit a wall immediately. (Randallbsmith (talk) 22:17, 27 January 2008 (UTC))

I don't believe it is properly defined. By taking Tr_v you should end up with an element of L(W) not L(V). Maybe its just a difference in conventional notation, but in quantum information theory you call Tr_b(p) as "tracing out" system b and you end up with an element of the other system. So the only difference is changing the subscript to the part you are tracing, not the part that stays unchanged. —Preceding unsigned comment added by 173.52.93.17 (talk) 05:42, 16 December 2009 (UTC)

I fully agree, it's wrongly defined. Tr_v should be replaced by Tr_w throughout the whole article. 82.130.80.182 (talk) 14:12, 10 February 2010 (UTC)

Yes, I also noticed that the Tr_V and Tr_W notation were mixed up (an understandable mistake). Enough people have complained here that I am pretty confident it's not just that we are unaware of alternate convention. I'll fix. Njerseyguy (talk) 15:58, 10 February 2010 (UTC)

References please

The article reads like the author had a textbook or some notes handy. Could you please add a reference to it? Thisrod 00:42, 19 June 2006 (UTC)

New visualization of the partial trace

Hi everyone,

I recently added a new visualization for the partial trace to complement the description section. My goal was to make the concept a bit more intuitive for a small tripartite system.

What do you think about the description of the figure? The description feels a bit clunky. Please feel free to tweak it directly. Feedback is highly appreciated! Thanks Axean97 (talk) 11:40, 14 March 2026 (UTC)