Parity-time electromagnetic diodes in a two-dimensional nonreciprocal photonic crystal

We propose a kind of electromagnetic (EM) diode based on a two-dimensional nonreciprocal gyrotropic photonic crystal. This periodic microstructure has separately broken symmetries in both parity (P) and time-reversal (T) but obeys parity-time (PT) symmetry. This kind of diode could support bulk one-way propagating modes either for group velocity or phase velocity with various types of negative and positive refraction. This symmetry-broken system could be a platform to realize abnormal photoelectronic devices, and it may be analogous to an electron counterpart with one-way features

Triaqua­(2,2′-bipyridine N,N′-dioxide-κ2 O,O′)(5-nitro­benzene-1,3-dicarboxyl­ato-κO 1)zinc(II)

In the title compound, [Zn(C8H3NO6)(C10H8N2O2)(H2O)3], the ZnII ion is coordinated in a distorted octa­hedral geometry by three water mol­ecules, one O atom from a 5-nitro­benzene-1,3-dicarboxyl­ate ligand and two O atoms from a chelating 2,2′-bipyridine N,N′-dioxide ligand. An extensive network of O—H⋯O hydrogen bonds is formed between the water mol­ecules and the carboxyl­ate groups. C—H⋯O inter­actions are also present

Light-cone Sum Rule Analysis of Semileptonic Decays Λb0→Λc+ℓ−ν‾ℓ\Lambda_b^0 \to \Lambda_c^+ \ell^- \overline{\nu}_\ell

In this work, we analyze the semileptonic decay processes of $\Lambda_b \to \Lambda_c$ in the light-cone sum rule approach. In the calculation of the form factors of $\Lambda_b$ baryon transition matrix element, the light-cone distribution amplitudes of $\Lambda_b$ which are obtained from QCD sum rule in the heavy quark effective field theory framework are used. With the calculation of the six form factors of $\Lambda_b \to \Lambda_c$ transition matrix element, the differential decay widths of $\Lambda_b^0 \to \Lambda_c^+ \ell^- \overline{\nu}_\ell (\ell = e, \mu, \tau)$ and absolute branching fractions are obtained. Additionally the ratio of $R(\Lambda_c)=\mathcal{B}r(\Lambda_b\to \Lambda_c e \nu_e)/\mathcal{B}r(\Lambda_b \to \Lambda_c \tau \nu_\tau)$ is obtained. These results are in accordance with the newest experimental result and other theoretical calculations and predictions.Comment: 10 pages,6 figure

One-way cloak based on nonreciprocal photonic crystal

We propose a physical concept of non-reciprocal transformation optics, by which a one-way invisible cloak is designed. The one-way invisible cloak is made of a coordinate-transformed nonreciprocal photonic crystal, showing a perfect cloaking for wave incident from one direction but acting as a perfect reflector for wave from the counter direction. The proposed design shows a high promise of applications in military, as protecting the own information to be detected but efficiently grabbing the information from the “enemy” side

Mesoscopic Kondo screening effect in a single-electron transistor embedded in a metallic ring

We study the Kondo screening effect generated by a single-electron transistor or quantum dot embedded in a small metallic ring. When the ring circumference $L$ becomes comparable to the fundamental length scale $\xi_K^0=\hbar \upsilon _F/T_K^0$ associated with the {\it bulk} Kondo tempe the Kondo resonance is strongly affected, depending on the total number of electrons ({\it modulo} 4) and magnetic flux threading the ring. The resulting Kondo-assisted persistent currents are also calculated in both Kondo and mixed valence regimes, and the maximum values are found in the crossover region.Comment: 4 pages, Revtex, 6 figures, more references are include

Valence bond spin liquid state in two-dimensional frustrated spin-1/2 Heisenberg antiferromagnets

Fermionic valence bond approach in terms of SU(4) representation is proposed to describe the $J_{1}-J_{2}$ frustrated Heisenberg antiferromagnetic (AF) model on a {\it bipartite} square lattice. A uniform mean field solution without breaking the translational and rotational symmetries describes a valence bond spin liquid state, interpolating the two different AF ordered states in the large $J_{1}$ and large $J_{2}$ limits, respectively. This novel spin liquid state is gapless with the vanishing density of states at the Fermi nodal points. Moreover, a sharp resonance peak in the dynamic structure factor is predicted for momenta ${\bf q}=(0,0)$ and $(\pi ,\pi)$ in the strongly frustrated limit $J_{2}/J_{1}\sim 1/2$, which can be checked by neutron scattering experiment.Comment: Revtex file, 4 pages, 4 figure

Tunable Unidirectional Sound Propagation through a Sonic-Crystal-Based Acoustic Diode

Nonreciprocal wave propagation typically requires strong nonlinear materials to break time reversal symmetry. Here, we utilized a sonic-crystal-based acoustic diode that had broken spatial inversion symmetry and experimentally realized sound unidirectional transmission in this acoustic diode. These novel phenomena are attributed to different mode transitions as well as their associated different energy conversion efficiencies among different diffraction orders at two sides of the diode. This nonreciprocal sound transmission could be systematically controlled by simply mechanically rotating the square rods of the sonic crystal. Different from nonreciprocity due to the nonlinear acoustic effect and broken time reversal symmetry, this new model leads to a one-way effect with higher efficiency, broader bandwidth, and much less power consumption, showing promising applications in various sound devices