Finding Traps in Non-linear Spin Arrays

Precise knowledge of the Hamiltonian of a system is a key to many of its applications. Tasks such state transfer or quantum computation have been well studied with a linear chain, but hardly with systems, which do not possess a linear structure. While this difference does not disturb the end-to-end dynamics of a single excitation, the evolution is significantly changed in other subspaces. Here we quantify the difference between a linear chain and a pseudo-chain, which have more than one spin at some site (block). We show how to estimate a number of all spins in the system and the intra-block coupling constants. We also suggest how it is possible to eliminate excitations trapped in such blocks, which may disturb the state transfer. Importantly, one uses only at-ends data and needs to be able to put the system to either the maximally magnetized or the maximally mixed state. This can obtained by controlling a global decoherence parameter, such as temperature.Comment: 5 pages, 1 figur

Translating Concepts of State Transfer to Spin-1 Chains

State transfer is a well-known routine for various systems of spins-$\frac{1}2$. Still, it is not well studied for chains of spins of larger magnitudes. In this contribution we argue that while perfect state transfer may seem unnatural in spin-1 systems, it is still feasible for arrays of V-type three-level atoms. Tomography of such 1D array is also shown to be possible by acting on one atom from such an array