# Start a new discussion

## Not signed in

Want to take part in these discussions? Sign in if you have an account, or apply for one below

## Site Tag Cloud

Vanilla 1.1.10 is a product of Lussumo. More Information: Documentation, Community Support.

• CommentRowNumber1.
• CommentAuthorIan_Durham
• CommentTimeMar 7th 2010
Just added a page on partial trace that is presently linked from quantum operations and channels which I also added to. However, note that the partial trace is not specific to physics so it needs embellishing by the mathematicians among us.
• CommentRowNumber2.
• CommentAuthorUrs
• CommentTimeMar 8th 2010

Thanks.

the trace of an endomorphism is defined in any bradied monoidal category with duals (such as Vect): in string diagram notation you simply draw the morphism as a line and then bend that line around and connect its output to its input.

Now, it that morphism is the endomorphism of a tensor product object $V \otimes W$, then there is a similarly evident way to "bend around" only the W-strand. That's the partial trace operation.

This is very simple once one draws the diagram, which I won't do right now.

• CommentRowNumber3.
• CommentAuthorUrs
• CommentTimeMar 8th 2010

See trace, which should also be interlinked with partial trace

• CommentRowNumber4.
• CommentAuthorIan_Durham
• CommentTimeMar 8th 2010
Cool! I'll link them up when I get the chance (probably later today). I have to learn how to draw diagrams on nLab, but when I do I can add the diagrams you mentioned.