Quantum Networks on Cubelike Graphs

Cubelike graphs are the Cayley graphs of the elementary abelian group (Z_2)^n (e.g., the hypercube is a cubelike graph). We give conditions for perfect state transfer between two particles in quantum networks modeled by a large class of cubelike graphs. This generalizes results of Christandl et al. [Phys. Rev. Lett. 92, 187902 (2004)] and Facer et al. [Phys. Rev. A 92, 187902 (2008)].Comment: 5 pages, 2 eps figure

On the multiple Borsuk numbers of sets

The Borsuk number of a set S of diameter d >0 in Euclidean n-space is the smallest value of m such that S can be partitioned into m sets of diameters less than d. Our aim is to generalize this notion in the following way: The k-fold Borsuk number of such a set S is the smallest value of m such that there is a k-fold cover of S with m sets of diameters less than d. In this paper we characterize the k-fold Borsuk numbers of sets in the Euclidean plane, give bounds for those of centrally symmetric sets, smooth bodies and convex bodies of constant width, and examine them for finite point sets in the Euclidean 3-space.Comment: 16 pages, 3 figure

On the multiple Borsuk numbers of sets

The \emph{Borsuk number} of a set $S$ of diameter $d >0$ in Euclidean $n$-space is the smallest value of $m$ such that $S$ can be partitioned into $m$ sets of diameters less than $d$. Our aim is to generalize this notion in the following way: The \emph{$k$-fold Borsuk number} of such a set $S$ is the smallest value of $m$ such that there is a $k$-fold cover of $S$ with $m$ sets of diameters less than $d$. In this paper we characterize the $k$-fold Borsuk numbers of sets in the Euclidean plane, give bounds for those of centrally symmetric sets, smooth bodies and convex bodies of constant width, and examine them for finite point sets in the Euclidean $3$-space