Spin chains have been proposed as quantum wires in many quantum-information processing architectures. Coherent transmission of quantum information in spin chains over short distances is enabled by their internal dynamics, which drives the transport of single-spin excitations in perfectly polarized chains. Given the practical challenge of preparing the chain in a pure state, we propose to use a ...

It is shown that only a fraction of 2−Ω(n) of the graphs on n vertices have an integral spectrum. Although there are several explicit constructions of such graphs, no upper bound for their number has been known. Graphs of this type play an important role in quantum networks supporting the so-called perfect state transfer. AMS Subject Classification: 05C50, 05C80

Roussel and Rubio proved a lemma which is essential in the proof of the Strong Perfect Graph Theorem. We give a new short proof of the main case of this lemma. In this note, we also give a short proof of Hayward’s decomposition theorem for weakly chordal graphs, relying on a Roussel–Rubio-type lemma. We recall how Roussel–Rubio-type lemmas yield very short proofs of the existence of even pairs ...

Analytic mass-spring chains with dispersionless pulse transfer and fractional revival are presented. These obtained using the properties of para-Racah polynomials. This provides classical analogs quantum spin that realize important tasks in information: perfect state entanglement generation.

One of the most striking consequences of quantum physics is quantum teleportation - the possibility to transfer quantum states over arbitrary distances. Since its theoretical introduction, teleportation has been demonstrated experimentally up to the distance of 143 km. In the original proposal two parties share a maximally entangled quantum state acting as a resource for the teleportation task....

We will extend Reed's Semi-Strong Perfect Graph Theorem by proving that unbreakable C 5-free graphs diierent from a C 6 and its complement have unique P 4-structure.

The continuous-time quantum walk is a basic model for studying transport and developing quantum-enhanced algorithms. Recent studies show that by introducing phase into the standard model, time-reversal symmetry can be broken without changing Hermitian property of Hamiltonian. breaking shows advantages in transport, such as perfect state transfer, directional control, speedup, efficiency enhance...

The Wonderful Lemma, that was first proved by Roussel and Rubio, is one of the most important tools in the proof of the Strong Perfect Graph Theorem. Here we give a short proof of this lemma.