Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 11236

For questions about mathematical problems arising from quantum mechanics, a branch of physics describing the behaviour of nature at very small scales, at the level of atoms and subatomic particles.

11 votes

Linear algebra underlying quantum entanglement?

Many introductory books on quantum information theory go over the linear algebraic tools necessary to study the topic, including the tensor product (since it indeed models quantum entanglement). Takin …
Nathaniel Johnston's user avatar
3 votes

Is the set of two-qubit absolutely separable states convex, and if so, what are its John ell...

There are two slightly different questions here (even without discussing John ellipsoids, which I do not know the answer to), so I'll try to be careful in my answer. Question 1: Is the set of absolute …
Nathaniel Johnston's user avatar
3 votes

Traceless Hermitian matrices with simultaneously vanishing Rayleigh quotients

I'll prove some bounds that disprove the conjectured $N = D^2 - 2$ when $D \geq 3$. Bound 1: $N \leq D(D-1)$. I'll illustrate this bound when $D = 3$ (so $N \leq 6$). Consider the following 7 of the …
Nathaniel Johnston's user avatar
1 vote
Accepted

Traceless Hermitian matrices with simultaneously vanishing Rayleigh quotients

The correct value of $N$ is $$ N = \begin{cases} 2 & \text{if $D = 2$},\\ 3 & \text{if $D \geq 3$}. \end{cases} $$ The original question already proved that $N = 2$ when $D = 2$, and Michał's answer h …
Nathaniel Johnston's user avatar