Rarita-Schwinger-Weyl semimetal in Jeff=3/2 electron systems

We propose a relativistic Jeff=3/2 semimetal with 4d1 or 5d1 electrons on a cubic lattice when the strong spin-orbital coupling takes over the Hunds' coupling. A relativistic spinor with spin 3/2 is historically called Rarita-Schwinger spinor. In the massless case, the right- and left-handed chiral degrees of freedom of the Rarita-Schwinger spinors are independent. In the lattice model that we propose, the right- and left- handed gapless points in Brillouin zone are separated. We call this linearly dispersed semimetal Rarita-Schwinger-Weyl semimetal, similar to Weyl semimetal for spin 1/2 systems. There is a network of gapless Fermi arcs in the surface Brillouin zone if n1+n2+n3 is even for the normal vector (n1,n2,n3) of the surface while the surface is insulator if n1+n2+n3 is odd.Comment: 5 pages, 4 figure

On unusual narrow transmission bands for a multi-layered periodic structure containing left-handed materials

A multi-layered structure consisting of alternate right-handed material (RHM) and left-handed material (LHM)is considered and the unusual narrow transmission bands are explained as the competitive results of the Bragg condition and the transparent condition. These unusual narrow transmission bands may exist regardless whether the optical length of the LHM layer cancels the optical length of the RHM layer or not. This unusual transmission property may disappear when the reflection coefficient for each interface is small and the optical length of the LHM layer does not cancel the optical length of the RHM layer. An non-ideal model when the LHM is dispersive and lossy is also employed to confirm the unusual transmission phenomenon.Comment: 9 pages, 4 figure

Study of cascade ring-closing metathesis reactions en route to an advanced intermediate of Taxol

A highly functionalized intermediate in the synthesis of Taxol has been synthesized, which features the tricyclic core and the required oxygen substituents at C1, C2, C7, C10 and C13. The key step, a ring-closing dienyne metathesis (RCDEYM) reaction, has been thoroughly optimized to favor the tricyclic product over the undesired bicyclic product resulting from diene metathesis

Observation of Fast Evolution in Parity-Time-Symmetric System

To find and realize the optimal evolution between two states is significant both in theory and application. In quantum mechanics, the minimal evolution is bounded by the gap between the largest and smallest eigenvalue of the Hamiltonian. In the parity-time-symmetric(PT-symmetric) Hamiltonian theory, it was predicted that the optimized evolution time can be reduced drastically comparing to the bound in the Hermitian case, and can become even zero. In this Letter, we report the experimental observation of the fast evolution of a PT-symmetric Hamiltonian in an nuclear magnetic resonance (NMR) quantum system. The experimental results demonstrate that the PT-symmetric Hamiltonian can indeed evolve much faster than that in a quantum system, and time it takes can be arbitrary close to zero.Comment: 13 pages, 5 figure